Adaptive rateless coding for sidelink communications

ABSTRACT

Methods, systems, and devices for wireless communications are described. A first user equipment (UE) may receive and decode a network-coded message over a sidelink channel from a second UE, the network-coded message encoded using a rateless encoding algorithm. The first UE may report redundancy feedback information to the second UE for the network-coded message. Based on the feedback information, the second UE may adjust an amount of redundancy used to encode future messages to the first UE that are encoded using the rateless encoding algorithm.

FIELD OF TECHNOLOGY

The following relates to wireless communications, including adaptiverateless coding for sidelink communications.

BACKGROUND

Wireless communications systems are widely deployed to provide varioustypes of communication content such as voice, video, packet data,messaging, broadcast, and so on. These systems may be capable ofsupporting communication with multiple users by sharing the availablesystem resources (e.g., time, frequency, and power). Examples of suchmultiple-access systems include fourth generation (4G) systems such asLong Term Evolution (LTE) systems, LTE-Advanced (LTE-A) systems, orLTE-A Pro systems, and fifth generation (5G) systems which may bereferred to as New Radio (NR) systems. These systems may employtechnologies such as code division multiple access (CDMA), time divisionmultiple access (TDMA), frequency division multiple access (FDMA),orthogonal FDMA (OFDMA), or discrete Fourier transform spread orthogonalfrequency division multiplexing (DFT-S-OFDM). A wireless multiple-accesscommunications system may include one or more base stations or one ormore network access nodes, each simultaneously supporting communicationfor multiple communication devices, which may be otherwise known as userequipment (UE).

SUMMARY

The described techniques relate to improved methods, systems, devices,and apparatuses that support adaptive rateless coding for sidelinkcommunications. Generally, a first user equipment (UE) that receives anddecodes a network-coded packet (e.g., a packet encoded using a ratelessencoding algorithm) over a sidelink channel from a second UE (e.g., atransmitting UE) may report redundancy feedback information to thetransmitting UE for the network-coded packet. The transmitting UE mayadjust the amount of redundancy for the rateless encoding for futurepackets transmitted to the first UE (the receiving UE) based on thereported redundancy feedback information. An original set of parametersfor network coding on the sidelink, including, for example, a firstamount of redundancy, a quantity of subpackets into which to divide eachpacket, a rateless encoding algorithm, and a rateless decodingalgorithm, may be transmitted by a base station to the transmitting UEand the receiving UE via control signaling. The transmitting UE mayencode and transmit a first packet according to the first set ofparameters, and the receiving UE may decode the first packet accordingto the first set of parameters. The receiving UE may report networkcoding redundancy feedback information to the transmitting UE based onthe decoding. The transmitting UE may encode a second packet using therateless encoding algorithm and in accordance with a second amount ofredundancy based on the network coding redundancy feedback information,and the transmitting UE may transmit the second encoded packet to thereceiving UE.

A method for wireless communications at a first user UE is described.The method may include receiving, from a base station, signaling thatindicates a first amount of redundancy for encoding using a ratelessencoding algorithm, encoding a first packet using the rateless encodingalgorithm and in accordance with the first amount of redundancy toobtain an encoded first packet, transmitting the encoded first packet toa second UE via a sidelink channel, receiving, from the second UE, amessage including information that indicates a sufficiency of the firstamount of redundancy for encoding using the rateless encoding algorithm,encoding a second packet using the rateless encoding algorithm and inaccordance with a second amount of redundancy to obtain an encodedsecond packet, the second amount of redundancy different than the firstamount of redundancy and based on the sufficiency of the first amount ofredundancy for encoding using the rateless encoding algorithm, andtransmitting the encoded second packet to the second UE via the sidelinkchannel.

An apparatus for wireless communications at a first UE is described. Theapparatus may include a memory, a transceiver, and at least oneprocessor in communication with the memory and the transceiver. The atleast one processor may be configured to cause the apparatus to receive,from a base station, signaling that indicates a first amount ofredundancy for encoding using a rateless encoding algorithm, encode afirst packet using the rateless encoding algorithm and in accordancewith the first amount of redundancy to obtain an encoded first packet,transmit the encoded first packet to a second UE via a sidelink channel,receive, from the second UE, a message including information thatindicates a sufficiency of the first amount of redundancy for encodingusing the rateless encoding algorithm, encode a second packet using therateless encoding algorithm and in accordance with a second amount ofredundancy to obtain an encoded second packet, the second amount ofredundancy different than the first amount of redundancy and based onthe sufficiency of the first amount of redundancy for encoding using therateless encoding algorithm, and transmit the encoded second packet tothe second UE via the sidelink channel.

Another apparatus for wireless communications at a first UE isdescribed. The apparatus may include means for receiving, from a basestation, signaling that indicates a first amount of redundancy forencoding using a rateless encoding algorithm, means for encoding a firstpacket using the rateless encoding algorithm and in accordance with thefirst amount of redundancy to obtain an encoded first packet, means fortransmitting the encoded first packet to a second UE via a sidelinkchannel, means for receiving, from the second UE, a message includinginformation that indicates a sufficiency of the first amount ofredundancy for encoding using the rateless encoding algorithm, means forencoding a second packet using the rateless encoding algorithm and inaccordance with a second amount of redundancy to obtain an encodedsecond packet, the second amount of redundancy different than the firstamount of redundancy and based on the sufficiency of the first amount ofredundancy for encoding using the rateless encoding algorithm, and meansfor transmitting the encoded second packet to the second UE via thesidelink channel.

A non-transitory computer-readable medium storing code for wirelesscommunications at a first UE is described. The code may includeinstructions executable by a processor to receive, from a base station,signaling that indicates a first amount of redundancy for encoding usinga rateless encoding algorithm, encode a first packet using the ratelessencoding algorithm and in accordance with the first amount of redundancyto obtain an encoded first packet, transmit the encoded first packet toa second UE via a sidelink channel, receive, from the second UE, amessage including information that indicates a sufficiency of the firstamount of redundancy for encoding using the rateless encoding algorithm,encode a second packet using the rateless encoding algorithm and inaccordance with a second amount of redundancy to obtain an encodedsecond packet, the second amount of redundancy different than the firstamount of redundancy and based on the sufficiency of the first amount ofredundancy for encoding using the rateless encoding algorithm, andtransmit the encoded second packet to the second UE via the sidelinkchannel.

In some examples of the method, apparatuses, and non-transitorycomputer-readable medium described herein, the information thatindicates the sufficiency of the first amount of redundancy may bepacket-level information that indicates the sufficiency of the firstamount of redundancy.

In some examples of the method, apparatuses, and non-transitorycomputer-readable medium described herein, the information thatindicates the sufficiency of the first amount of redundancy indicates anestimated loss probability for the first packet, and the method,apparatuses, and non-transitory computer-readable medium may includefurther operations, features, means, or instructions for determining thesecond amount of redundancy based on the estimated loss probability.

In some examples of the method, apparatuses, and non-transitorycomputer-readable medium described herein, determining the second amountof redundancy based on the estimated loss probability may includeoperations, features, means, or instructions for identifying the secondamount of redundancy based on an index value for a lookup table, wherethe index value for the lookup table corresponds to the estimated lossprobability.

In some examples of the method, apparatuses, and non-transitorycomputer-readable medium described herein, receiving the messageincluding the information that indicates the sufficiency of the firstamount of redundancy may include operations, features, means, orinstructions for receiving, in the message, an indication of the secondamount of redundancy.

In some examples of the method, apparatuses, and non-transitorycomputer-readable medium described herein, receiving the messageincluding the information that indicates the sufficiency of the firstamount of redundancy may include operations, features, means, orinstructions for receiving, in the message, a request to decrease aredundancy amount for encoding using the rateless encoding algorithm,where the second amount of redundancy may be less than the first amountof redundancy.

In some examples of the method, apparatuses, and non-transitorycomputer-readable medium described herein, receiving the messageincluding the information that indicates the sufficiency of the firstamount of redundancy may include operations, features, means, orinstructions for receiving, in the message, a request to increase aredundancy amount for encoding using the rateless encoding algorithm,where the second amount of redundancy may be greater than the firstamount of redundancy.

In some examples of the method, apparatuses, and non-transitorycomputer-readable medium described herein, receiving the messageincluding the information that indicates the sufficiency of the firstamount of redundancy may include operations, features, means, orinstructions for receiving, in the message, an indication of whether thefirst packet was successfully decoded, where the second amount ofredundancy may be based on the indication.

In some examples of the method, apparatuses, and non-transitorycomputer-readable medium described herein, encoding the first packetusing the rateless encoding algorithm may include operations, features,means, or instructions for dividing the first packet into a set ofsubpackets including a first quantity of subpackets and generating a setof encoded subpackets based on the set of subpackets and using therateless encoding algorithm, where the set of encoded subpacketsincludes a second quantity of encoded subpackets that may be greaterthan the first quantity of subpackets, and where an amount of redundancyfor encoding using the rateless encoding algorithm includes a differencebetween the second quantity of encoded subpackets and the first quantityof subpackets.

Some examples of the method, apparatuses, and non-transitorycomputer-readable medium described herein may further includeoperations, features, means, or instructions for receiving, from thesecond UE, a second message including information that indicates asecond sufficiency of the second amount of redundancy for encoding usingthe rateless encoding algorithm, transmitting, to the base station andbased on the information that indicates the second sufficiency of thesecond amount of redundancy for encoding using the rateless encodingalgorithm, a request to switch from using the rateless encodingalgorithm to using a different rateless encoding algorithm for sidelinkcommunications, receiving, from the base station, an indication of asecond rateless encoding algorithm that includes the different ratelessencoding algorithm, encoding a third packet using the second ratelessencoding algorithm to obtain an encoded third packet, and transmittingthe encoded third packet to the second UE via the sidelink channel.

In some examples of the method, apparatuses, and non-transitorycomputer-readable medium described herein, the information thatindicates the second sufficiency of the second amount of redundancy maybe packet-level information that indicates the second sufficiency of thesecond amount of redundancy.

Some examples of the method, apparatuses, and non-transitorycomputer-readable medium described herein may further includeoperations, features, means, or instructions for receiving an indicationof a quantity of subpackets into which to divide each packet forencoding using the rateless encoding algorithm, an indication of therateless encoding algorithm, an indication of a rateless decodingalgorithm, an indication of a pool of transmission resources forsidelink communications by the first UE, or any combination thereof.

A method for wireless communications at a second UE is described. Themethod may include receiving, from a base station, signaling thatindicates a first amount of redundancy for encoding using a ratelessencoding algorithm, receiving, from a first UE via a sidelink channel, apacket encoded using the rateless encoding algorithm and in accordancewith the first amount of redundancy, decoding the packet using arateless decoding algorithm that corresponds to the rateless encodingalgorithm, and transmitting, to the first UE based on decoding thepacket using the rateless decoding algorithm, a message includinginformation that indicates a sufficiency of the first amount ofredundancy for encoding using the rateless encoding algorithm.

An apparatus for wireless communications at a second UE is described.The apparatus may include a memory, a transceiver, and at least oneprocessor in communication with the memory and the transceiver. The atleast one processor may be configured to cause the apparatus to receive,from a base station, signaling that indicates a first amount ofredundancy for encoding using a rateless encoding algorithm, receive,from a first UE via a sidelink channel, a packet encoded using therateless encoding algorithm and in accordance with the first amount ofredundancy, decode the packet using a rateless decoding algorithm thatcorresponds to the rateless encoding algorithm, and transmit, to thefirst UE based on decoding the packet using the rateless decodingalgorithm, a message including information that indicates a sufficiencyof the first amount of redundancy for encoding using the ratelessencoding algorithm.

Another apparatus for wireless communications at a second UE isdescribed. The apparatus may include means for receiving, from a basestation, signaling that indicates a first amount of redundancy forencoding using a rateless encoding algorithm, means for receiving, froma first UE via a sidelink channel, a packet encoded using the ratelessencoding algorithm and in accordance with the first amount ofredundancy, means for decoding the packet using a rateless decodingalgorithm that corresponds to the rateless encoding algorithm, and meansfor transmitting, to the first UE based on decoding the packet using therateless decoding algorithm, a message including information thatindicates a sufficiency of the first amount of redundancy for encodingusing the rateless encoding algorithm.

A non-transitory computer-readable medium storing code for wirelesscommunications at a second UE is described. The code may includeinstructions executable by a processor to receive, from a base station,signaling that indicates a first amount of redundancy for encoding usinga rateless encoding algorithm, receive, from a first UE via a sidelinkchannel, a packet encoded using the rateless encoding algorithm and inaccordance with the first amount of redundancy, decode the packet usinga rateless decoding algorithm that corresponds to the rateless encodingalgorithm, and transmit, to the first UE based on decoding the packetusing the rateless decoding algorithm, a message including informationthat indicates a sufficiency of the first amount of redundancy forencoding using the rateless encoding algorithm.

In some examples of the method, apparatuses, and non-transitorycomputer-readable medium described herein, the information thatindicates the sufficiency of the first amount of redundancy may bepacket-level information that indicates the sufficiency of the firstamount of redundancy.

Some examples of the method, apparatuses, and non-transitorycomputer-readable medium described herein may further includeoperations, features, means, or instructions for estimating a lossprobability for the packet, where the information that indicates thesufficiency of the first amount of redundancy for encoding using therateless encoding algorithm indicates the estimated loss probability forthe packet.

In some examples of the method, apparatuses, and non-transitorycomputer-readable medium described herein, estimating the lossprobability for the packet may include operations, features, means, orinstructions for determining a first quantity of subpackets received bythe second UE during a time period and a second quantity of subpacketstransmitted by the first UE during the time period, the loss probabilitybased on a ratio between the first quantity of subpackets received bythe second UE and the second quantity of subpackets transmitted by thefirst UE during the time period.

Some examples of the method, apparatuses, and non-transitorycomputer-readable medium described herein may further includeoperations, features, means, or instructions for estimating a lossprobability for the packet and determining a second amount of redundancybased on the estimated loss probability for the packet, where theinformation that indicates the sufficiency of the first amount ofredundancy for encoding using the rateless encoding algorithm indicatesthe second amount of redundancy.

In some examples of the method, apparatuses, and non-transitorycomputer-readable medium described herein, determining the second amountof redundancy based on the estimated loss probability may includeoperations, features, means, or instructions for identifying the secondamount of redundancy based on an index value for a lookup table, wherethe index value for the lookup table corresponds to the estimated lossprobability.

In some examples of the method, apparatuses, and non-transitorycomputer-readable medium described herein, transmitting the messageincluding the information that indicates the sufficiency of the firstamount of redundancy may include operations, features, means, orinstructions for transmitting, in the message, a request to increase aredundancy amount.

In some examples of the method, apparatuses, and non-transitorycomputer-readable medium described herein, transmitting the messageincluding the information that indicates the sufficiency of the firstamount of redundancy may include operations, features, means, orinstructions for transmitting, in the message, a request to decrease aredundancy amount.

In some examples of the method, apparatuses, and non-transitorycomputer-readable medium described herein, transmitting the messageincluding the information that indicates the sufficiency of the firstamount of redundancy may include operations, features, means, orinstructions for transmitting, in the message, an indication of whetherthe packet was successfully decoded.

In some examples of the method, apparatuses, and non-transitorycomputer-readable medium described herein, decoding the packet using therateless decoding algorithm may include operations, features, means, orinstructions for identifying a set of encoded subpackets received forthe packet, the set of encoded subpackets including a first quantity ofencoded subpackets greater than or equal to a second quantity oforiginal subpackets encoded using the rateless encoding algorithm,decoding the set of encoded subpackets to obtain a set of decodedsubpackets including a third quantity of decoded subpackets, the thirdquantity greater than or equal to the second quantity, and attempting toobtain the packet based on the set of decoded subpackets.

In some examples of the method, apparatuses, and non-transitorycomputer-readable medium described herein, a probability of success fordecoding the packet using the rateless decoding algorithm may be basedon a difference between the first quantity of encoded subpackets and thesecond quantity of original subpackets.

Some examples of the method, apparatuses, and non-transitorycomputer-readable medium described herein may further includeoperations, features, means, or instructions for transmitting, to thebase station, a request to transmit the information that indicates thesufficiency of the first amount of redundancy for encoding using therateless encoding algorithm and receiving, from the base station, agrant in response to the request, where the message including theinformation that indicates the sufficiency of the first amount ofredundancy for encoding using the rateless encoding algorithm may betransmitted based on the grant from the base station.

Some examples of the method, apparatuses, and non-transitorycomputer-readable medium described herein may further includeoperations, features, means, or instructions for transmitting therequest to transmit the information that indicates the sufficiency ofthe first amount of redundancy for encoding using the rateless encodingalgorithm may be based on one of a condition of the sidelink channel ora quality of service target associated with the sidelink channel.

Some examples of the method, apparatuses, and non-transitorycomputer-readable medium described herein may further includeoperations, features, means, or instructions for receiving, from thebase station, a request to transmit the information that indicates thesufficiency of the first amount of redundancy for encoding using therateless encoding algorithm, where transmitting the message includingthe information that indicates the sufficiency of the first amount ofredundancy for encoding using the rateless encoding algorithm may betransmitted based on the request from the base station.

Some examples of the method, apparatuses, and non-transitorycomputer-readable medium described herein may further includeoperations, features, means, or instructions for receiving, from thefirst UE via the sidelink channel, a second packet encoded using therateless encoding algorithm and in accordance with a second amount ofredundancy different than the first amount of redundancy, the secondamount of redundancy different than the first amount of redundancy andbased on the sufficiency of the first amount of redundancy for encodingusing the rateless encoding algorithm.

Some examples of the method, apparatuses, and non-transitorycomputer-readable medium described herein may further includeoperations, features, means, or instructions for receiving an indicationof a quantity of original subpackets for the packet encoded using therateless encoding algorithm, an indication of the rateless encodingalgorithm, an indication of the rateless decoding algorithm, anindication of a pool of transmission resources for sidelinkcommunications by the second UE, or any combination thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a wireless communications system thatsupports adaptive rateless coding for sidelink communications inaccordance with aspects of the present disclosure.

FIG. 2 illustrates an example of a wireless communications system thatsupports adaptive rateless coding for sidelink communications inaccordance with aspects of the present disclosure.

FIG. 3 illustrates an example of an encoding process that supportsadaptive rateless coding for sidelink communications in accordance withaspects of the present disclosure.

FIG. 4 illustrates an example of a wireless communications system thatsupports adaptive rateless coding for sidelink communications inaccordance with aspects of the present disclosure.

FIG. 5 illustrates an example of a protocol stack diagram that supportsadaptive rateless coding for sidelink communications in accordance withaspects of the present disclosure.

FIG. 6 illustrates an example of a process flow that supports adaptiverateless coding for sidelink communications in accordance with aspectsof the present disclosure.

FIGS. 7 and 8 show block diagrams of devices that support adaptiverateless coding for sidelink communications in accordance with aspectsof the present disclosure.

FIG. 9 shows a block diagram of a communications manager that supportsadaptive rateless coding for sidelink communications in accordance withaspects of the present disclosure.

FIG. 10 shows a diagram of a system including a device that supportsadaptive rateless coding for sidelink communications in accordance withaspects of the present disclosure.

FIGS. 11 through 19 show flowcharts illustrating methods that supportadaptive rateless coding for sidelink communications in accordance withaspects of the present disclosure.

DETAILED DESCRIPTION

In some wireless communications systems, a user equipment (UE) maycommunicate with one or more other UEs via sidelink connections. Someexamples of sidelink communications may be device-to-device (D2D)communications, vehicle-to-vehicle (V2V) communications,vehicle-to-everything (V2X), etc. In some examples, a UE may use asidelink connection with a neighboring UE to obtain or relay missedinformation from a previous downlink transmission. Some wirelesscommunications systems may use network coding schemes (e.g., codingschemes using a rateless encoding algorithm) to improve reliability oftransmissions. For example, a transmitter (e.g., a transmitting UE or abase station) may divide an original packet into k original subpacketsand encode and transmit N subpackets to reliably send the k originalsubpackets of the packet to a receiving UE, where N>k. The differencebetween N and k may correspond to an amount of redundancy of the networkcoding scheme. A receiver (e.g., a receiving UE) may receive and decodeat least a number (e.g., M) of subpackets to recover the original packetwith a desired probability (e.g., 99%), where M is less than N, butgreater than k.

The amount of subpackets M to be received to decode the k subpacketswith the desired probability may be dependent upon channel conditionsbetween the transmitter and receiver. Network coding may be used on adirect link between a base station and one or more UEs or on sidelinksbetween multiple UEs. In some examples, for UEs communicating with agiven base station, the decodable set size M is fixed for a fixed numberof subpackets k in order to achieve a desired decoding successprobability based on channel conditions of the direct link. Channelconditions on the sidelinks between the UEs may be different from thechannel conditions of the direct link, however. Therefore, if an amountof redundancy for all receiving devices is identical (e.g., inflexible),then some resources may be utilized inefficiently and some transmissionsmay be more likely to fail.

For example, a transmitting base station in communication with tworeceiving UEs may communicate via direct communication links having alow path loss. Additionally or alternatively, a transmitting UE maycommunicate with a receiving UE via a sidelink having a high path loss.If the transmitting UE encodes and transmits signaling on the sidelinkusing the same redundancy configuration (e.g., network coding with asame N value for a set quantity of subpackets k) as the base station onthe direct link, then transmission on the sidelink may not besuccessfully received (e.g., because the redundancy configuration of thenetwork encoding on the sidelink is not high enough to compensate forthe high packet loss). Or if the sidelink has a lower path loss than thedirect link, transmissions on the sidelink may unnecessarily utilizemore resources than necessary (e.g., introducing more redundancy thannecessary and utilizing extra resources that may have otherwise beenavailable for use for other communications). Thus, a fixed networkcoding redundancy for a sidelink configuration may result in inefficientuse of available resources, failed transmissions, increased systemlatency, decreased reliability of communications, and decreased userexperience.

A UE receiving messages (the receiving UE) via a sidelink channel fromanother UE (the transmitting UE) may report redundancy feedbackinformation to the transmitting UE, and the transmitting UE may adjustthe amount of redundancy for the network coding for future messagingbased on the reported redundancy feedback information. In some cases,the reported redundancy feedback information may be packet-levelinformation, where packet-level information may refer to informationthat is associated with an entire packet (e.g., obtained by thereceiving UE based on attempting to decode one or more entire packets astransmitted by the transmitting UE).

An original set of parameters for network coding on the sidelink may bereceived by the transmitting UE and the receiving UE from the basestation via control signaling. The original set of parameters fornetwork coding on the sidelink may include, for example, a first amountof redundancy, a quantity of subpackets into which to divide eachpacket, a rateless encoding algorithm, and a corresponding ratelessdecoding algorithm. The transmitting UE may encode and transmit a firstpacket according to the first set of parameters, and the receiving UEmay decode the first packet according to the first set of parameters.The receiving UE may report the network coding redundancy feedbackinformation (e.g., packet-level redundancy feedback information) to thetransmitting UE based on the decoding.

For example, the receiving UE may transmit, to the transmitting UE,redundancy feedback information that may include an estimated packetloss probability calculated by the receiving UE (e.g., based onattempting to decode one or more entire packets). The loss probability(p_loss) may be estimated as the number of received subpackets dividedby the total amount of subpackets transmitted over a given period oftime T (e.g., where the total amount of transmitted subpackets of theperiod T correspond to one or more entire packets). The transmitting UEmay adjust the amount of redundancy based on the reported lossprobability. In some cases, the receiving UE may transmit, to thetransmitting UE, redundancy feedback information that may include arequested amount of redundancy (e.g., based on attempting to decode oneor more entire packets). For example, the receiving UE may calculate thedesired amount of redundancy R as R=M/(1−p_loss)−k. The receiving UE mayindicate the desired amount of redundancy to the transmitting UE. Insome cases, the receiving UE may transmit, to the transmitting UE,redundancy feedback information that may include a request to increaseor decrease the amount of redundancy by a given amount, for examplebased on whether the receiving UE successfully decoded one or morepackets. In some cases, the receiving UE may transmit, to thetransmitting UE, redundancy feedback information that may include adetermination that decoding was successful or unsuccessful for one ormore packets. The transmitting UE may increase or decrease the amount ofredundancy based on whether the one or more packets were successfullydecoded.

In some cases, if the receiving UE continues to fail to decode packetstransmitted over the sidelink after redundancy amount updates by thetransmitting UE, the transmitting UE may request updated network codingalgorithms and associated parameters from the base station. For example,if the receiving UE indicates a threshold number of times that an amountof redundancy should be increased or that multiple subsequent packetswere unsuccessfully decoded, the transmitting UE may request updatednetwork coding algorithms and associated parameters from the basestation. In response, the base station may transmit updated networkcoding algorithms and associated parameters to the transmitting UE andthe receiving UE. In some examples, the transmitting UE may requestupdated network coding algorithms and associated parameters from thebase station based on changing sidelink channel conditions or based onchanging sidelink quality of service targets.

In some examples, the base station may activate or deactivate (e.g., viaa medium access control (MAC) control element (MAC-CE) signal or adownlink control information (DCI) message) the ability of the receivingUE to report redundancy feedback information to the transmitting UE, forexample based on sidelink channel conditions or sidelink quality ofservice targets. The receiving UE may request, for example, via a MAC-CEsignal or an uplink control information (UCI) signal (e.g., over thedirect link), to activate or deactivate the ability to redundancyfeedback information to the transmitting UE, for example based onsidelink channel conditions or sidelink quality of service targets.

Aspects of the disclosure are initially described in the context ofwireless communications systems. Aspects of the disclosure are furtherillustrated by and described with reference to encoding processes,wireless communications systems, protocol stack diagrams and processflows. Aspects of the disclosure are further illustrated by anddescribed with reference to apparatus diagrams, system diagrams, andflowcharts that relate to adaptive rateless coding for sidelinkcommunications.

FIG. 1 illustrates an example of a wireless communications system 100that supports adaptive rateless coding for sidelink communications inaccordance with aspects of the present disclosure. The wirelesscommunications system 100 may include one or more base stations 105, oneor more UEs 115, and a core network 130. In some examples, the wirelesscommunications system 100 may be a Long Term Evolution (LTE) network, anLTE-Advanced (LTE-A) network, an LTE-A Pro network, or a New Radio (NR)network. In some examples, the wireless communications system 100 maysupport enhanced broadband communications, ultra-reliablecommunications, low latency communications, communications with low-costand low-complexity devices, or any combination thereof.

The base stations 105 may be dispersed throughout a geographic area toform the wireless communications system 100 and may be devices indifferent forms or having different capabilities. The base stations 105and the UEs 115 may wirelessly communicate via one or more communicationlinks 125. Each base station 105 may provide a coverage area 110 overwhich the UEs 115 and the base station 105 may establish one or morecommunication links 125. The coverage area 110 may be an example of ageographic area over which a base station 105 and a UE 115 may supportthe communication of signals according to one or more radio accesstechnologies.

The UEs 115 may be dispersed throughout a coverage area 110 of thewireless communications system 100, and each UE 115 may be stationary,or mobile, or both at different times. The UEs 115 may be devices indifferent forms or having different capabilities. Some example UEs 115are illustrated in FIG. 1 . The UEs 115 described herein may be able tocommunicate with various types of devices, such as other UEs 115, thebase stations 105, or network equipment (e.g., core network nodes, relaydevices, integrated access and backhaul (IAB) nodes, or other networkequipment), as shown in FIG. 1 .

The base stations 105 may communicate with the core network 130, or withone another, or both. For example, the base stations 105 may interfacewith the core network 130 through one or more backhaul links 120 (e.g.,via an S1, N2, N3, or other interface). The base stations 105 maycommunicate with one another over the backhaul links 120 (e.g., via anX2, Xn, or other interface) either directly (e.g., directly between basestations 105), or indirectly (e.g., via core network 130), or both. Insome examples, the backhaul links 120 may be or include one or morewireless links.

One or more of the base stations 105 described herein may include or maybe referred to by a person having ordinary skill in the art as a basetransceiver station, a radio base station, an access point, a radiotransceiver, a NodeB, an eNodeB (eNB), a next-generation NodeB or agiga-NodeB (either of which may be referred to as a gNB), a Home NodeB,a Home eNodeB, or other suitable terminology.

A UE 115 may include or may be referred to as a mobile device, awireless device, a remote device, a handheld device, or a subscriberdevice, or some other suitable terminology, where the “device” may alsobe referred to as a unit, a station, a terminal, or a client, amongother examples. A UE 115 may also include or may be referred to as apersonal electronic device such as a cellular phone, a personal digitalassistant (PDA), a tablet computer, a laptop computer, or a personalcomputer. In some examples, a UE 115 may include or be referred to as awireless local loop (WLL) station, an Internet of Things (IoT) device,an Internet of Everything (IoE) device, or a machine type communications(MTC) device, among other examples, which may be implemented in variousobjects such as appliances, or vehicles, meters, among other examples.

The UEs 115 described herein may be able to communicate with varioustypes of devices, such as other UEs 115 that may sometimes act as relaysas well as the base stations 105 and the network equipment includingmacro eNBs or gNBs, small cell eNBs or gNBs, or relay base stations,among other examples, as shown in FIG. 1 .

The UEs 115 and the base stations 105 may wirelessly communicate withone another via one or more communication links 125 over one or morecarriers. The term “carrier” may refer to a set of radio frequencyspectrum resources having a defined physical layer structure forsupporting the communication links 125. For example, a carrier used fora communication link 125 may include a portion of a radio frequencyspectrum band (e.g., a bandwidth part (BWP)) that is operated accordingto one or more physical layer channels for a given radio accesstechnology (e.g., LTE, LTE-A, LTE-A Pro, NR). Each physical layerchannel may carry acquisition signaling (e.g., synchronization signals,system information), control signaling that coordinates operation forthe carrier, user data, or other signaling. The wireless communicationssystem 100 may support communication with a UE 115 using carrieraggregation or multi-carrier operation. A UE 115 may be configured withmultiple downlink component carriers and one or more uplink componentcarriers according to a carrier aggregation configuration. Carrieraggregation may be used with both frequency division duplexing (FDD) andtime division duplexing (TDD) component carriers.

In some examples (e.g., in a carrier aggregation configuration), acarrier may also have acquisition signaling or control signaling thatcoordinates operations for other carriers. A carrier may be associatedwith a frequency channel (e.g., an evolved universal mobiletelecommunication system terrestrial radio access (E-UTRA) absoluteradio frequency channel number (EARFCN)) and may be positioned accordingto a channel raster for discovery by the UEs 115. A carrier may beoperated in a standalone mode where initial acquisition and connectionmay be conducted by the UEs 115 via the carrier, or the carrier may beoperated in a non-standalone mode where a connection is anchored using adifferent carrier (e.g., of the same or a different radio accesstechnology).

The communication links 125 shown in the wireless communications system100 may include uplink transmissions from a UE 115 to a base station105, or downlink transmissions from a base station 105 to a UE 115.Carriers may carry downlink or uplink communications (e.g., in an FDDmode) or may be configured to carry downlink and uplink communications(e.g., in a TDD mode).

A carrier may be associated with a particular bandwidth of the radiofrequency spectrum, and in some examples the carrier bandwidth may bereferred to as a “system bandwidth” of the carrier or the wirelesscommunications system 100. For example, the carrier bandwidth may be oneof a number of determined bandwidths for carriers of a particular radioaccess technology (e.g., 1.4, 3, 5, 10, 15, 20, 40, or 80 megahertz(MHz)). Devices of the wireless communications system 100 (e.g., thebase stations 105, the UEs 115, or both) may have hardwareconfigurations that support communications over a particular carrierbandwidth or may be configurable to support communications over one of aset of carrier bandwidths. In some examples, the wireless communicationssystem 100 may include base stations 105 or UEs 115 that supportsimultaneous communications via carriers associated with multiplecarrier bandwidths. In some examples, each served UE 115 may beconfigured for operating over portions (e.g., a sub-band, a BWP) or allof a carrier bandwidth.

Signal waveforms transmitted over a carrier may be made up of multiplesubcarriers (e.g., using multi-carrier modulation (MCM) techniques suchas orthogonal frequency division multiplexing (OFDM) or discrete Fouriertransform spread OFDM (DFT-S-OFDM)). In a system employing MCMtechniques, a resource element may consist of one symbol period (e.g., aduration of one modulation symbol) and one subcarrier, where the symbolperiod and subcarrier spacing are inversely related. The number of bitscarried by each resource element may depend on the modulation scheme(e.g., the order of the modulation scheme, the coding rate of themodulation scheme, or both). Thus, the more resource elements that a UE115 receives and the higher the order of the modulation scheme, thehigher the data rate may be for the UE 115. A wireless communicationsresource may refer to a combination of a radio frequency spectrumresource, a time resource, and a spatial resource (e.g., spatial layersor beams), and the use of multiple spatial layers may further increasethe data rate or data integrity for communications with a UE 115.

One or more numerologies for a carrier may be supported, where anumerology may include a subcarrier spacing (Δƒ) and a cyclic prefix. Acarrier may be divided into one or more BWPs having the same ordifferent numerologies. In some examples, a UE 115 may be configuredwith multiple BWPs. In some examples, a single BWP for a carrier may beactive at a given time and communications for the UE 115 may berestricted to one or more active BWPs.

The time intervals for the base stations 105 or the UEs 115 may beexpressed in multiples of a basic time unit which may, for example,refer to a sampling period of T_(s)=1/(Δƒ_(max)·N_(ƒ)) seconds, whereΔƒ_(max) may represent the maximum supported subcarrier spacing, andN_(ƒ) may represent the maximum supported discrete Fourier transform(DFT) size. Time intervals of a communications resource may be organizedaccording to radio frames each having a specified duration (e.g., 10milliseconds (ms)). Each radio frame may be identified by a system framenumber (SFN) (e.g., ranging from 0 to 1023).

Each frame may include multiple consecutively numbered subframes orslots, and each subframe or slot may have the same duration. In someexamples, a frame may be divided (e.g., in the time domain) intosubframes, and each subframe may be further divided into a number ofslots. Alternatively, each frame may include a variable number of slots,and the number of slots may depend on subcarrier spacing. Each slot mayinclude a number of symbol periods (e.g., depending on the length of thecyclic prefix prepended to each symbol period). In some wirelesscommunications systems 100, a slot may further be divided into multiplemini-slots containing one or more symbols. Excluding the cyclic prefix,each symbol period may contain one or more (e.g., N_(ƒ)) samplingperiods. The duration of a symbol period may depend on the subcarrierspacing or frequency band of operation.

A subframe, a slot, a mini-slot, or a symbol may be the smallestscheduling unit (e.g., in the time domain) of the wirelesscommunications system 100 and may be referred to as a transmission timeinterval (TTI). In some examples, the TTI duration (e.g., the number ofsymbol periods in a TTI) may be variable. Additionally or alternatively,the smallest scheduling unit of the wireless communications system 100may be dynamically selected (e.g., in bursts of shortened TTIs (sTTIs)).

Physical channels may be multiplexed on a carrier according to varioustechniques. A physical control channel and a physical data channel maybe multiplexed on a downlink carrier, for example, using one or more oftime division multiplexing (TDM) techniques, frequency divisionmultiplexing (FDM) techniques, or hybrid TDM-FDM techniques. A controlregion (e.g., a control resource set (CORESET)) for a physical controlchannel may be defined by a number of symbol periods and may extendacross the system bandwidth or a subset of the system bandwidth of thecarrier. One or more control regions (e.g., CORESETs) may be configuredfor a set of the UEs 115. For example, one or more of the UEs 115 maymonitor or search control regions for control information according toone or more search space sets, and each search space set may include oneor multiple control channel candidates in one or more aggregation levelsarranged in a cascaded manner. An aggregation level for a controlchannel candidate may refer to a number of control channel resources(e.g., control channel elements (CCEs)) associated with encodedinformation for a control information format having a given payloadsize. Search space sets may include common search space sets configuredfor sending control information to multiple UEs 115 and UE-specificsearch space sets for sending control information to a specific UE 115.

Each base station 105 may provide communication coverage via one or morecells, for example a macro cell, a small cell, a hot spot, or othertypes of cells, or any combination thereof. The term “cell” may refer toa logical communication entity used for communication with a basestation 105 (e.g., over a carrier) and may be associated with anidentifier for distinguishing neighboring cells (e.g., a physical cellidentifier (PCID), a virtual cell identifier (VCID), or others). In someexamples, a cell may also refer to a geographic coverage area 110 or aportion of a geographic coverage area 110 (e.g., a sector) over whichthe logical communication entity operates. Such cells may range fromsmaller areas (e.g., a structure, a subset of structure) to larger areasdepending on various factors such as the capabilities of the basestation 105. For example, a cell may be or include a building, a subsetof a building, or exterior spaces between or overlapping with geographiccoverage areas 110, among other examples.

A macro cell generally covers a relatively large geographic area (e.g.,several kilometers in radius) and may allow unrestricted access by theUEs 115 with service subscriptions with the network provider supportingthe macro cell. A small cell may be associated with a lower-powered basestation 105, as compared with a macro cell, and a small cell may operatein the same or different (e.g., licensed, unlicensed) frequency bands asmacro cells. Small cells may provide unrestricted access to the UEs 115with service subscriptions with the network provider or may providerestricted access to the UEs 115 having an association with the smallcell (e.g., the UEs 115 in a closed subscriber group (CSG), the UEs 115associated with users in a home or office). A base station 105 maysupport one or multiple cells and may also support communications overthe one or more cells using one or multiple component carriers.

In some examples, a carrier may support multiple cells, and differentcells may be configured according to different protocol types (e.g.,MTC, narrowband IoT (NB-IoT), enhanced mobile broadband (eMBB)) that mayprovide access for different types of devices.

In some examples, a base station 105 may be movable and thereforeprovide communication coverage for a moving geographic coverage area110. In some examples, different geographic coverage areas 110associated with different technologies may overlap, but the differentgeographic coverage areas 110 may be supported by the same base station105. In other examples, the overlapping geographic coverage areas 110associated with different technologies may be supported by differentbase stations 105. The wireless communications system 100 may include,for example, a heterogeneous network in which different types of thebase stations 105 provide coverage for various geographic coverage areas110 using the same or different radio access technologies.

The wireless communications system 100 may support synchronous orasynchronous operation. For synchronous operation, the base stations 105may have similar frame timings, and transmissions from different basestations 105 may be approximately aligned in time. For asynchronousoperation, the base stations 105 may have different frame timings, andtransmissions from different base stations 105 may, in some examples,not be aligned in time. The techniques described herein may be used foreither synchronous or asynchronous operations.

Some UEs 115, such as MTC or IoT devices, may be low cost or lowcomplexity devices and may provide for automated communication betweenmachines (e.g., via Machine-to-Machine (M2M) communication). M2Mcommunication or MTC may refer to data communication technologies thatallow devices to communicate with one another or a base station 105without human intervention. In some examples, M2M communication or MTCmay include communications from devices that integrate sensors or metersto measure or capture information and relay such information to acentral server or application program that makes use of the informationor presents the information to humans interacting with the applicationprogram. Some UEs 115 may be designed to collect information or enableautomated behavior of machines or other devices. Examples ofapplications for MTC devices include smart metering, inventorymonitoring, water level monitoring, equipment monitoring, healthcaremonitoring, wildlife monitoring, weather and geological eventmonitoring, fleet management and tracking, remote security sensing,physical access control, and transaction-based business charging.

Some UEs 115 may be configured to employ operating modes that reducepower consumption, such as half-duplex communications (e.g., a mode thatsupports one-way communication via transmission or reception, but nottransmission and reception simultaneously). In some examples,half-duplex communications may be performed at a reduced peak rate.Other power conservation techniques for the UEs 115 include entering apower saving deep sleep mode when not engaging in active communications,operating over a limited bandwidth (e.g., according to narrowbandcommunications), or a combination of these techniques. For example, someUEs 115 may be configured for operation using a narrowband protocol typethat is associated with a defined portion or range (e.g., set ofsubcarriers or resource blocks (RBs)) within a carrier, within aguard-band of a carrier, or outside of a carrier.

The wireless communications system 100 may be configured to supportultra-reliable communications or low-latency communications, or variouscombinations thereof. For example, the wireless communications system100 may be configured to support ultra-reliable low-latencycommunications (URLLC). The UEs 115 may be designed to supportultra-reliable, low-latency, or critical functions. Ultra-reliablecommunications may include private communication or group communicationand may be supported by one or more services such as push-to-talk,video, or data. Support for ultra-reliable, low-latency functions mayinclude prioritization of services, and such services may be used forpublic safety or general commercial applications. The termsultra-reliable, low-latency, and ultra-reliable low-latency may be usedinterchangeably herein.

In some examples, a UE 115 may also be able to communicate directly withother UEs 115 over a device-to-device (D2D) communication link 135(e.g., using a peer-to-peer (P2P) or D2D protocol). One or more UEs 115utilizing D2D communications may be within the geographic coverage area110 of a base station 105. Other UEs 115 in such a group may be outsidethe geographic coverage area 110 of a base station 105 or be otherwiseunable to receive transmissions from a base station 105. In someexamples, groups of the UEs 115 communicating via D2D communications mayutilize a one-to-many (1:M) system in which each UE 115 transmits toevery other UE 115 in the group. In some examples, a base station 105facilitates the scheduling of resources for D2D communications. In othercases, D2D communications are carried out between the UEs 115 withoutthe involvement of a base station 105.

In some systems, the D2D communication link 135 may be an example of acommunication channel, such as a sidelink communication channel, betweenvehicles (e.g., UEs 115). In some examples, vehicles may communicateusing vehicle-to-everything (V2X) communications, vehicle-to-vehicle(V2V) communications, or some combination of these. A vehicle may signalinformation related to traffic conditions, signal scheduling, weather,safety, emergencies, or any other information relevant to a V2X system.In some examples, vehicles in a V2X system may communicate with roadsideinfrastructure, such as roadside units, or with the network via one ormore network nodes (e.g., base stations 105) using vehicle-to-network(V2N) communications, or with both.

The core network 130 may provide user authentication, accessauthorization, tracking, Internet Protocol (IP) connectivity, and otheraccess, routing, or mobility functions. The core network 130 may be anevolved packet core (EPC) or 5G core (5GC), which may include at leastone control plane entity that manages access and mobility (e.g., amobility management entity (MME), an access and mobility managementfunction (AMF)) and at least one user plane entity that routes packetsor interconnects to external networks (e.g., a serving gateway (S-GW), aPacket Data Network (PDN) gateway (P-GW), or a user plane function(UPF)). The control plane entity may manage non-access stratum (NAS)functions such as mobility, authentication, and bearer management forthe UEs 115 served by the base stations 105 associated with the corenetwork 130. User IP packets may be transferred through the user planeentity, which may provide IP address allocation as well as otherfunctions. The user plane entity may be connected to IP services 150 forone or more network operators. The IP services 150 may include access tothe Internet, Intranet(s), an IP Multimedia Subsystem (IMS), or aPacket-Switched Streaming Service.

Some of the network devices, such as a base station 105, may includesubcomponents such as an access network entity 140, which may be anexample of an access node controller (ANC). Each access network entity140 may communicate with the UEs 115 through one or more other accessnetwork transmission entities 145, which may be referred to as radioheads, smart radio heads, or transmission/reception points (TRPs). Eachaccess network transmission entity 145 may include one or more antennapanels. In some configurations, various functions of each access networkentity 140 or base station 105 may be distributed across various networkdevices (e.g., radio heads and ANCs) or consolidated into a singlenetwork device (e.g., a base station 105).

The wireless communications system 100 may operate using one or morefrequency bands, typically in the range of 300 megahertz (MHz) to 300gigahertz (GHz). Generally, the region from 300 MHz to 3 GHz is known asthe ultra-high frequency (UHF) region or decimeter band because thewavelengths range from approximately one decimeter to one meter inlength. The UHF waves may be blocked or redirected by buildings andenvironmental features, but the waves may penetrate structuressufficiently for a macro cell to provide service to the UEs 115 locatedindoors. The transmission of UHF waves may be associated with smallerantennas and shorter ranges (e.g., less than 100 kilometers) compared totransmission using the smaller frequencies and longer waves of the highfrequency (HF) or very high frequency (VHF) portion of the spectrumbelow 300 MHz.

The wireless communications system 100 may also operate in a super highfrequency (SHF) region using frequency bands from 3 GHz to 30 GHz, alsoknown as the centimeter band, or in an extremely high frequency (EHF)region of the spectrum (e.g., from 30 GHz to 300 GHz), also known as themillimeter band. In some examples, the wireless communications system100 may support millimeter wave (mmW) communications between the UEs 115and the base stations 105, and EHF antennas of the respective devicesmay be smaller and more closely spaced than UHF antennas. In someexamples, this may facilitate use of antenna arrays within a device. Thepropagation of EHF transmissions, however, may be subject to evengreater atmospheric attenuation and shorter range than SHF or UHFtransmissions. The techniques disclosed herein may be employed acrosstransmissions that use one or more different frequency regions, anddesignated use of bands across these frequency regions may differ bycountry or regulating body.

The wireless communications system 100 may utilize both licensed andunlicensed radio frequency spectrum bands. For example, the wirelesscommunications system 100 may employ License Assisted Access (LAA),LTE-Unlicensed (LTE-U) radio access technology, or NR technology in anunlicensed band such as the 5 GHz industrial, scientific, and medical(ISM) band. When operating in unlicensed radio frequency spectrum bands,devices such as the base stations 105 and the UEs 115 may employ carriersensing for collision detection and avoidance. In some examples,operations in unlicensed bands may be based on a carrier aggregationconfiguration in conjunction with component carriers operating in alicensed band (e.g., LAA). Operations in unlicensed spectrum may includedownlink transmissions, uplink transmissions, P2P transmissions, or D2Dtransmissions, among other examples.

A base station 105 or a UE 115 may be equipped with multiple antennas,which may be used to employ techniques such as transmit diversity,receive diversity, multiple-input multiple-output (MIMO) communications,or beamforming. The antennas of a base station 105 or a UE 115 may belocated within one or more antenna arrays or antenna panels, which maysupport MIMO operations or transmit or receive beamforming. For example,one or more base station antennas or antenna arrays may be co-located atan antenna assembly, such as an antenna tower. In some examples,antennas or antenna arrays associated with a base station 105 may belocated in diverse geographic locations. A base station 105 may have anantenna array with a number of rows and columns of antenna ports thatthe base station 105 may use to support beamforming of communicationswith a UE 115. Likewise, a UE 115 may have one or more antenna arraysthat may support various MIMO or beamforming operations. Additionally oralternatively, an antenna panel may support radio frequency beamformingfor a signal transmitted via an antenna port.

The base stations 105 or the UEs 115 may use MIMO communications toexploit multipath signal propagation and increase the spectralefficiency by transmitting or receiving multiple signals via differentspatial layers. Such techniques may be referred to as spatialmultiplexing. The multiple signals may, for example, be transmitted bythe transmitting device via different antennas or different combinationsof antennas. Likewise, the multiple signals may be received by thereceiving device via different antennas or different combinations ofantennas. Each of the multiple signals may be referred to as a separatespatial stream and may carry bits associated with the same data stream(e.g., the same codeword) or different data streams (e.g., differentcodewords). Different spatial layers may be associated with differentantenna ports used for channel measurement and reporting. MIMOtechniques include single-user MIMO (SU-MIMO), where multiple spatiallayers are transmitted to the same receiving device, and multiple-userMIMO (MU-MIMO), where multiple spatial layers are transmitted tomultiple devices.

Beamforming, which may also be referred to as spatial filtering,directional transmission, or directional reception, is a signalprocessing technique that may be used at a transmitting device or areceiving device (e.g., a base station 105, a UE 115) to shape or steeran antenna beam (e.g., a transmit beam, a receive beam) along a spatialpath between the transmitting device and the receiving device.Beamforming may be achieved by combining the signals communicated viaantenna elements of an antenna array such that some signals propagatingat particular orientations with respect to an antenna array experienceconstructive interference while others experience destructiveinterference. The adjustment of signals communicated via the antennaelements may include a transmitting device or a receiving deviceapplying amplitude offsets, phase offsets, or both to signals carriedvia the antenna elements associated with the device. The adjustmentsassociated with each of the antenna elements may be defined by abeamforming weight set associated with a particular orientation (e.g.,with respect to the antenna array of the transmitting device orreceiving device, or with respect to some other orientation).

A base station 105 or a UE 115 may use beam sweeping techniques as partof beam forming operations. For example, a base station 105 may usemultiple antennas or antenna arrays (e.g., antenna panels) to conductbeamforming operations for directional communications with a UE 115.Some signals (e.g., synchronization signals, reference signals, beamselection signals, or other control signals) may be transmitted by abase station 105 multiple times in different directions. For example,the base station 105 may transmit a signal according to differentbeamforming weight sets associated with different directions oftransmission. Transmissions in different beam directions may be used toidentify (e.g., by a transmitting device, such as a base station 105, orby a receiving device, such as a UE 115) a beam direction for latertransmission or reception by the base station 105.

Some signals, such as data signals associated with a particularreceiving device, may be transmitted by a base station 105 in a singlebeam direction (e.g., a direction associated with the receiving device,such as a UE 115). In some examples, the beam direction associated withtransmissions along a single beam direction may be determined based on asignal that was transmitted in one or more beam directions. For example,a UE 115 may receive one or more of the signals transmitted by the basestation 105 in different directions and may report to the base station105 an indication of the signal that the UE 115 received with a highestsignal quality or an otherwise acceptable signal quality.

In some examples, transmissions by a device (e.g., by a base station 105or a UE 115) may be performed using multiple beam directions, and thedevice may use a combination of digital precoding or radio frequencybeamforming to generate a combined beam for transmission (e.g., from abase station 105 to a UE 115). The UE 115 may report feedback thatindicates precoding weights for one or more beam directions, and thefeedback may correspond to a configured number of beams across a systembandwidth or one or more sub-bands. The base station 105 may transmit areference signal (e.g., a cell-specific reference signal (CRS), achannel state information reference signal (CSI-RS)), which may beprecoded or unprecoded. The UE 115 may provide feedback for beamselection, which may be a precoding matrix indicator (PMI) orcodebook-based feedback (e.g., a multi-panel type codebook, a linearcombination type codebook, a port selection type codebook). Althoughthese techniques are described with reference to signals transmitted inone or more directions by a base station 105, a UE 115 may employsimilar techniques for transmitting signals multiple times in differentdirections (e.g., for identifying a beam direction for subsequenttransmission or reception by the UE 115) or for transmitting a signal ina single direction (e.g., for transmitting data to a receiving device).

A receiving device (e.g., a UE 115) may try multiple receiveconfigurations (e.g., directional listening) when receiving varioussignals from the base station 105, such as synchronization signals,reference signals, beam selection signals, or other control signals. Forexample, a receiving device may try multiple receive directions byreceiving via different antenna subarrays, by processing receivedsignals according to different antenna subarrays, by receiving accordingto different receive beamforming weight sets (e.g., differentdirectional listening weight sets) applied to signals received atmultiple antenna elements of an antenna array, or by processing receivedsignals according to different receive beamforming weight sets appliedto signals received at multiple antenna elements of an antenna array,any of which may be referred to as “listening” according to differentreceive configurations or receive directions. In some examples, areceiving device may use a single receive configuration to receive alonga single beam direction (e.g., when receiving a data signal). The singlereceive configuration may be aligned in a beam direction determinedbased on listening according to different receive configurationdirections (e.g., a beam direction determined to have a highest signalstrength, highest signal-to-noise ratio (SNR), or otherwise acceptablesignal quality based on listening according to multiple beamdirections).

The wireless communications system 100 may be a packet-based networkthat operates according to a layered protocol stack. In the user plane,communications at the bearer or Packet Data Convergence Protocol (PDCP)layer may be IP-based. A Radio Link Control (RLC) layer may performpacket segmentation and reassembly to communicate over logical channels.A Medium Access Control (MAC) layer may perform priority handling andmultiplexing of logical channels into transport channels. The MAC layermay also use error detection techniques, error correction techniques, orboth to support retransmissions at the MAC layer to improve linkefficiency. In the control plane, the Radio Resource Control (RRC)protocol layer may provide establishment, configuration, and maintenanceof an RRC connection between a UE 115 and a base station 105 or a corenetwork 130 supporting radio bearers for user plane data. At thephysical layer, transport channels may be mapped to physical channels.

The UEs 115 and the base stations 105 may support retransmissions ofdata to increase the likelihood that data is received successfully.Hybrid automatic repeat request (HARQ) feedback is one technique forincreasing the likelihood that data is received correctly over acommunication link 125. HARQ may include a combination of errordetection (e.g., using a cyclic redundancy check (CRC)), forward errorcorrection (FEC), and retransmission (e.g., automatic repeat request(ARQ)). HARQ may improve throughput at the MAC layer in poor radioconditions (e.g., low signal-to-noise conditions). In some examples, adevice may support same-slot HARQ feedback, where the device may provideHARQ feedback in a specific slot for data received in a previous symbolin the slot. In other cases, the device may provide HARQ feedback in asubsequent slot, or according to some other time interval.

A first UE 115 within the geographic coverage area 110 of a base station105 may transmit network-coded packets (e.g., packets encoded using arateless encoding algorithm in accordance with an amount of redundancy)to a second UE 115 within the geographic coverage area 110 via asidelink communication link 135. A base station 105 may transmit, overdirect communication links 125, a configuration message to the UEs 115including one or more parameters associated with a network codingconfiguration for data packets transmitted between the UEs 115 via thesidelink communication link 135. In some examples, the one or moreparameters may be configured by an RRC configuration. For example,parameters associated with a network coding configuration may include acoding amount of redundancy, a rateless encoding algorithm, a quantityof subpackets into which to divide each packet for encoding using therateless encoding algorithm, a corresponding rateless decodingalgorithm, or a pool of transmission resources for the sidelinkcommunication link 135.

After receiving the encoded packet from the first UE 115, the second UE115 may decode the packet using the rateless decoding algorithm thatcorresponds to the rateless encoding algorithm and transmit a feedbackmessage to the first UE 115 that indicates a sufficiency of theconfigured amount of redundancy for encoding using the rateless encodingalgorithm. The feedback message may indicate that the configured amountof redundancy is sufficient for encoding using the rateless encodingalgorithm, or, alternatively, the feedback message may indicate that theconfigured amount of redundancy is insufficient for encoding using therateless encoding algorithm. The feedback message may in some casesinclude packet-level information (e.g., information based on the secondUE 115 attempting to decode at least one entire packet transmitted bythe first UE 115). The first UE 115 may adjust the amount of redundancybased on the feedback message and encode future packets for transmissionto the second UE 115 using the adjusted amount of redundancy.

For example, the second UE 115 may transmit, to the first UE 115,redundancy feedback information that may include an estimated packetloss probability calculated by the second UE 115. The loss probability(p_loss) may be estimated as the number of received subpackets dividedby the total amount of subpackets transmitted over a period of time T.In some cases, the second UE 115 may transmit, to the first UE 115,redundancy feedback information that may include a requested amount ofredundancy. For example, the second UE 115 may calculate the desiredredundancy R as R=M/(1−p_loss)−k. The second UE 115 may indicate thedesired redundancy to the first UE 115 in the redundancy feedbackmessage. In some cases, the second UE 115 may transmit, to the first UE115, redundancy feedback information that may include a request toincrease or decrease the redundancy by a given amount, for example basedon whether the second UE 115 successfully decoded a received packet. Insome cases, the second UE 115 may transmit, to the first UE 115,redundancy feedback information that may include a determination thatdecoding was successful or unsuccessful. The first UE 115 may increaseor decrease the amount of redundancy based on whether the packet wassuccessfully decoded.

In some cases, if the second UE 115 continues to fail to decode packetstransmitted over the sidelink communication link 135 after redundancyupdates by the first UE 115, the first UE 115 may request updatednetwork coding algorithms and associated parameters from the basestation. For example, if the second UE 115 indicates a threshold numberof times that an amount of redundancy should be increased or thatmultiple subsequent packets were unsuccessfully decoded, the first UE115 may request updated network coding algorithms and associatedparameters from the base station 105. In response, the base station 105may transmit updated network coding algorithms and associated parametersto the first UE 115 and the second UE 115. In some examples, the firstUE 115 may request updated network coding algorithms and associatedparameters from the base station 105 based on changing sidelink channelconditions or based on changing sidelink quality of service targets.

In some examples, the base station 105 may activate or deactivate, forexample via a MAC-CE signal or a DCI signal, the ability of the secondUE 115 to report redundancy feedback information to the first UE 115,for example based on channel conditions for sidelink communication link135 or sidelink quality of service targets. The second UE 115 mayrequest, for example, via a MAC-CE signal or an UCI signal (e.g., overthe direct communication link 125), to activate or deactivate theability to redundancy feedback information to the first UE 115, forexample based on sidelink channel conditions or sidelink quality ofservice targets.

FIG. 2 illustrates an example of a wireless communications system 200that supports adaptive rateless coding for sidelink communications inaccordance with aspects of the present disclosure. In some examples,wireless communications system 200 may implement or may be implementedby aspects of wireless communications system 100. For example, thewireless communications system 200 may include a base station 105-a,which may be an example of a base station 105 as described herein, andUE 115-a, UE 115-b, and UE 115-c which may be examples of UEs 115 asdescribed herein.

The base station 105-a may communicate with one or more UEs 115. Forexample, the base station 105-a may communicate with UE 115-a via directlink 210-a, UE 115-b via direct link 210-b, and UE 115-c via direct link210-c. Additionally or alternatively, at least some of the UEs 115 maycommunicate with each other via sidelink connections. For example, UE115-a may communicate with UE 115-b using sidelink connection 220-a, UE115-b may communicate with UE 115-c using sidelink connection 220-c andUE 115-c may communicate with UE 115-a using sidelink connection 220-b.

In some examples, the sidelink connections 220 may be configured by thebase station 105-a. For example, the base station 105-a may configurecommunications and reporting for the sidelink connections 220. Forexample, the base station 105-a may transmit grants for sidelinkcommunications to the UEs 115. The base station 105-a may indicateallocated resources, carrier frequencies, modulation and coding schemevalues, transmission start and end times, etc. for communications on asidelink connection 220. In some cases, the UEs 115 may communicate onthe sidelink connections 220 according to the configurations from thebase station 105-a.

The wireless communications system 200 may support network codingprocedures (e.g., coding using rateless encoding and rateless decodingalgorithms). Network coding may enable devices to create a function ofinformation from a set of data packets and transmit the function of thedata packets to a UE 115 (e.g., network-coded packets). Network codingmay improve system efficiency and reliability. A device may generate aset of network-coded packets by merging some information from datapackets together into network-coded packets. For example, thenetwork-coded packets may include some information from each of the datapackets. For example, metadata from two separate data packets may bemerged into a network-coded packet. A receiver may be able to retrievethe original data packet if the receiver obtains sufficient informationfor the data packet from the network-coded packets. In some cases, thetransmitter and the receiver may have the same set of network codingparameters to encode and decode the network-coded packets, so that thereceiver and decode the network-coded packets and obtain the originaldata packets.

Network coding may in some cases be performed based on a ratelessencoding scheme (e.g., algorithm) and corresponding decoding scheme.Some examples of codes for use with rateless encoding schemes mayinclude fountain codes, such as Luby transform (LT) codes or rapidtornado (Raptor) codes. Raptor codes may be based on variations oflow-density parity check (LDPC) and LT codes. A rateless code may not beassociated with any fixed code rate (which may alternatively be referredto as coding rate). For example, a set of source symbols may be encodedusing a rateless code to generate any quantity of encoded symbols, andthe source symbols may be recovered based on decoding any sufficientlylarge group of encoded symbols—that is, it may not matter whichparticular encoded symbols are decoded by a receiving device, so long asa sufficient quantity of encoded symbols are decoded. In some examples,this may be because encoding the source symbols using a rateless code(e.g., fountain code) includes combining information related to one ormore source symbols into each encoded symbol. Encoded symbolscorresponding to (generated based on) a set of source symbols may betransmitted from a first node or device (which may be referred to as aninput node) of a network to a second node or device (which may bereferred to as an output node).

The base station 105-a may utilize network coding to transmit a messageto one or more UEs 115. For example, the base station 105-a may transmitnetwork-coded packets to the one or more UEs 115 via a direct links 210instead of transmitting each individual data packet. The base station105-a may indicate a set of network coding parameters to the one or moreUEs 115. The network coding parameters may be synchronized between thebase station 105-a and the one or more UEs 115 so that the one or moreUEs 115 may decode the network-coded packets and retrieve the originaldata packets. The set of network coding parameters may include, forexample, an encoding matrix, an encoding function, a decoding function,a quantity of subpackets into which to divide each packet, an amount ofredundancy, a number of decoding iterations (e.g., a maximum number ofdecoding iterations) or any combination thereof. In some cases, the basestation 105-a may configure the one or more UEs 115 with one or moresets of network coding parameters via the direct links 210.

Wireless communications systems described herein, such as the wirelesscommunications system 200, support sending network-coded packets on asidelink connection 220. For example, the UEs 115 may utilize networkcoding to generate network-coded packets and transmit network-codedinformation on sidelink connections. To support network codingtechniques on a sidelink connection, the base station 105-a mayconfigure the UEs 115 with one or more sets of network codingparameters. Configuring the UEs 115 with the one or more sets of networkcoding parameters may support transmission and decoding of network-codedpackets on a sidelink connection 220.

In some examples, a UE 115 may generate network-coded packets for thesidelink connection 220 using the same network coding parameters as thedirect links 210. For example, the base station 105-a may configure theUEs 115 with a set of network coding parameters. The set of networkcoding parameters may be used to generate network-coded packets whichare transmitted on the direct links 210. A UE 115 may use the set ofnetwork-coded parameters to encode data packets and transmit the encodedpackets to UEs 115 on a sidelink connection 220. For example, basestation 105-a may configure UE 115-a to encode data packets missing atUE 115-b using the set of network coding parameters. The base station105-a may configure UE 115-a to transmit functions of the data packetsto UE 115-b. UE 115-b may receive the encoded packets and use the set ofnetwork coding parameters to decode the packets. For example, UE 115-bmay decode the packets similar to decoding network-coded packetstransmitted on the direct links 210. UE 115-b may obtain the missingdata packets and send feedback to the base station 105-a to indicate thedata packets were successfully decoded. UE 115-a may similarly transmitnetwork-coded packets to UE 115-c for any missing data packets at UE115-c.

In some cases, the base station 105-a may configure the UEs 115 withmultiple sets of network coding parameters. For example, the basestation 105-a may preconfigure the UEs 115 with a first set of networkcoding parameters and a second set of network coding parameters. In someexamples, the UEs 115 may use the first set of coding parameters fordirect link communications and use the second set of coding parametersfor sidelink communications. Additionally or alternatively, the UEs 115may be configured with multiple sets of network coding parameters whichmay be used for the direct links 210, the sidelink connections 220, orboth. For example, the base station 105-a may configure UE 115-a toencode data packets missing at UE 115-b using the second set of networkcoding parameters. UE 115-a may transmit the function of the datapackets to UE 115-b on sidelink connection 220-a. UE 115-b may receivethe encoded packets, extract the second set of network coding parametersand decode the data packets. In some cases, UE 115-a may indicate thatthe second set of network coding parameters were used to generate thenetwork-coded packets sent on sidelink connection 220-a. UE 115-a maysimilarly transmit network-coded packets to UE 115-c for any missingdata packets at UE 115-c.

In some examples, network coding may be activated or deactivated for thesidelink connections 220. For example, the base station 105-a and theUEs 115 may activate or deactivate network coding based on channelquality, an overhead budget, or both. For example, if the channelquality is above a threshold or the overhead budget is below athreshold, network coding may be deactivated. For example, if networkcoding is deactivated, UE 115-a may send the original data packets tothe UEs 115 missing data packets. Alternatively, if the channel qualityvalue is below a threshold and the overhead budget is above a threshold,network coding may be activated. In some cases, the base station 105-amay activate or deactivate network coding on the sidelink connections.For example, the base station 105-a may determine the channel qualitybased on feedback from the UEs 115. The base station 105-a may indicateactivation or deactivation via a MAC-CE signal or DCI signal. In somecases, the UEs 115 may request to activate or deactivate network codingon the sidelink connections 220. For example, the UEs 115 may detectdata transmission quality on the sidelink connections 220 and send arequest to activate or deactivate network coding to the base station105-a. The request to activate or deactivate may be sent via a MAC-CEsignal or a UCI signal.

FIG. 3 illustrates an example of an encoding process 300 that supportsadaptive rateless coding for sidelink communications in accordance withaspects of the present disclosure. In some examples, encoding process300 may implement aspects of or may be implemented by aspects ofwireless communications systems 100 or 200. For example, encodingprocess 300 may use a fountain code, such as a rateless code that can beused by a base station 105 or a UEs 115 to encode a set of one or morepackets. Encoding process 300 may represent an example of an encodingprocess that a transmitting device or encoder (e.g., a base station 105or UE 115) may use when encoding a set of packets to transmit to areceiving device or decoder (e.g., a UE 115 or a base station 105). Inparticular, encoding process 300 may represent an example of such anencoding process that is based on an LT code.

The encoder may select a set of symbols from a symbol pool 305 to encodefor transmitting to the decoder. For example, the symbol pool 305 mayinclude k symbols 310, such as a first symbol 310-a, a second symbol310-b, a third symbol 310-c, a fourth symbol 310-d, a fifth symbol310-e, etc., to an k-th symbol 310-n. Each of the selected symbols 310from the symbol pool 305 may be encoded by the encoder (e.g., thetransmitting device, such as a UE 115, 115-a, 115-b, or 115-c or basestation 105 or 105-a) to one or more encoded symbols 315, such as afirst encoded symbol 315-a, a second encoded symbol 315-b, an m-thencoded symbol 315-m, and an n-th encoded symbol 315-n. The encoder mayencode a number N encoded symbols 315, where N>k. In some cases, theencoding of the symbols 310 to the encoded symbols 315 may depend on apacket pool encoding function, ƒ, on which the encoder is operating. Forexample, the packet pool encoding function, ƒ, may include the encoderdetermining a degree, d, of each encoded symbol 315.

The degree may be chosen at random from a given node degreedistribution, p(x). Subsequently, the encoder may choose ‘d’ distinctsymbols 310 (e.g., information symbols) from the symbol pool 305uniformly at random. These ‘d’ distinct symbols may be elements of theencoded symbol 315. For example, d=2 for the first encoding symbol 315-awith the fifth symbol 310-e and the n-th symbol 310-n being the elementsof the first encoding symbol 315-a, d=3 for the second encoding symbol315-b with the first symbol 310-a and the second symbol 310-b and thefourth symbol 310-d being the elements of the second encoding symbol315-b, d=2 for the m-th encoding symbol 315-m with the first symbol310-a and fifth symbol 310-e being the elements of the m-th encodingsymbol 315-m, and d=1 for the n-th encoding symbol 315-n with the thirdsymbol 310-c being the element of the n-th encoding symbol 315-n. Theencoder may assign an exclusive or (XOR) operation of the chosen ‘d’symbols 310 (e.g., information symbols) to the encoded symbol 315.

In some cases, an ideal solution distribution for the encoding processmay include P1=1/k or Pi=1/i(i−1) for i=2, 3, . . . , k, with krepresenting the number of symbols 310 in the symbol pool 305.Additionally or alternatively, a robust soliton distribution for theencoding process may include Mi=(Pi+Ti)/B, for i=1, 2, . . . , k, whereR/ik for i=1, . . . , k/R−1; Ti=R ln(R/δ)/k for i=k/R or Ti=0 for

${i = {\frac{k}{R} + 1}},\ldots,{k;}$

R=c ln(k/δ)√{square root over (k)}, where c is constant and δ is adecoding error probability; and B=sum(Pi+Ti) is a normalization factor.

Additionally or alternatively, a decodability threshold value, M (e.g.,a decodable threshold), may be defined for encoding process 300 (e.g.,using LT-based encoding). As long as a number of network encoded packetsor symbols received at a receiving device is greater than or equal to M,decoding of a message carried by the network encoded packets can besuccessful for the receiver. In some examples, if M=k, then the decodingsuccess probability for the receiving device may be up to 99%. If M=k+1,then the decoding success probability for the receiving device may be upto 99.99%. If M=k+2, then the decoding success probability for thereceiving device may be up to 99.9999%.

For a decodable set with M, k<M<N. The size of N may be increased toimprove reliability, or decreased to lessen unnecessary redundancy. Thatis, increased redundancy by an encoder may result in improved receptionat a receiving device. However, if redundancy is increased too much, thesystem may experience increased delays due to inefficient utilization ofavailable resources.

In some examples, as described in greater detail with reference to FIG.4 , a transmitting device may communicate with multiple receivingdevices via multiple communication links. Further, multiple transmittingdevices in a network (e.g., within the geographic coverage area 110 of abase station 105) may communicate via multiple links (e.g., with respectto FIG. 2 , a UEs 115-a, 115-b, or 115-c may communicate with a basestation 105-a via a direct links 210-a, 210-b, or 210-c). In suchexamples, different communication links (e.g., between a transmittingdevice and multiple receiving devices) may experience different channelconditions, resulting in different packet losses on the differentcommunication links. If the amount of redundancy for all receivingdevices is identical (e.g., inflexible), then some resources may beutilized inefficiently, and some transmissions may be more likely tofail.

For example, as illustrated in FIG. 2 , a transmitting device (e.g., UE115-a) may communicate with a base station 105-a via a direct link 210-aand with another UE 115-b via a sidelink connection 220-a. The sidelinkconnection 220-a may have a different path loss than the direct link210-a (e.g., the sidelink connection 220-a may have high path loss andthe direct link 210-a may have a low path loss, or vice versa). If theUE 115-a encodes and transmits signaling on both links using the sameredundancy configuration (e.g., network coding with a same N value),then the packet transmission on the sidelink connection 220-a may not besuccessfully decoded (e.g., because the redundancy configuration of thenetwork encoding on the sidelink connection 220-a is not high enough tocompensate for the high packet loss), while transmissions on the directlink 210-a may unnecessarily utilize more resources than necessary(e.g., introducing more redundancy than necessary and utilizing extraresources that could be used for other communications). Thus, a fixednetwork coding redundancy configuration (e.g., a fixed N value) mayresult in inefficient use of available resources, failed transmissions,increased system latency, decreased reliability of communications, anddecreased user experience.

A receiving UE 115, for example UE 115-b as illustrated in FIG. 2 , maysupport adaptive network, or rateless, coding for sidelinkcommunications, as described herein. For example, after receiving, froma transmitting UE 115-a via a sidelink connection 220-a, a network-codedpacket encoded using a rateless encoding algorithm according to a firstamount of redundancy, a receiving UE 115-b may decode the network-codedpacket using the rateless decoding algorithm that corresponds to therateless encoding algorithm used to encode the packet. The receiving UE115-b may transmit a feedback message to the transmitting UE 115-a thatindicates a sufficiency of the configured amount of redundancy forencoding using the rateless encoding algorithm. The feedback message mayindicate that the configured amount of redundancy is sufficient forencoding using the rateless encoding algorithm, or, alternatively, thefeedback message may indicate that the configured amount of redundancyis insufficient for encoding using the rateless encoding algorithm. Anyinformation described herein as included in such a feedback message mayin some cases be packet-level information (e.g., may be information thatis based on a receiving UE 115-b attempting to decode one or more entirepackets transmitted by a transmitting UE 115-a). The transmitting UE115-a may adjust the amount of redundancy for the rateless encodingalgorithm based on the redundancy feedback message, and encode futurepackets for transmission to the receiving UE 115-b using the adjustedamount of redundancy.

For example, the receiving UE 115-b may transmit, to the transmitting UE115-a, redundancy feedback information that may include an estimatedpacket loss probability calculated by the receiving UE 115-b. The lossprobability (p_loss) may be estimated as the number of receivedsubpackets divided by the total amount of subpackets transmitted over aperiod of time T. In some cases, the receiving UE 115-b may transmit, tothe transmitting UE 115-a, redundancy feedback information that mayinclude a requested amount of redundancy. For example, the receiving UE115-b may calculate the desired amount of redundancy R asR=M/(1−p_loss)−k. The receiving UE 115-b may indicate the desiredredundancy to the transmitting UE 115-a in the redundancy feedbackmessage. In some cases, the receiving UE 115-b may transmit, to thetransmitting UE 115-a, redundancy feedback information that may includea request to increase or decrease the redundancy by a given amount, forexample based on whether the receiving UE 115-b successfully decoded areceived packet. In some cases, the receiving UE 115-b may transmit, tothe transmitting UE 115-a, redundancy feedback information that mayinclude a determination that decoding was successful or unsuccessful.The transmitting UE 115-a may increase or decrease the amount ofredundancy based on whether the packet was successfully decoded.

In some cases, if the receiving UE 115-b continues to fail to decodepackets transmitted over the sidelink connection 220-a after redundancyupdates by the transmitting UE 115-a, the transmitting UE 115-a mayrequest updated network coding algorithms and associated parameters fromthe base station 105-a. For example, if the receiving UE 115-b indicatesa threshold number of times that an amount of redundancy should beincreased or that multiple subsequent packets were unsuccessfullydecoded, the transmitting UE 115-a may request updated network codingalgorithms and associated parameters from the base station 105-a. Inresponse, the base station 105-a may transmit updated network codingalgorithms and associated parameters to the transmitting UE 115-a andthe receiving UE 115-b. In some examples, the transmitting UE 115-a mayrequest updated network coding algorithms and associated parameters fromthe base station 105-a based on changing channel conditions for sidelinkconnection 220-a or based on changing sidelink quality of servicetargets.

In some examples, the base station 105-a may activate or deactivate, forexample via a MAC-CE signal or a DCI signal, the ability of thereceiving UE 115-b to report redundancy feedback information to thetransmitting UE 115-a, for example based on channel conditions forsidelink connection 220-a or sidelink quality of service targets. Thereceiving UE 115-b may request, for example, via a MAC-CE signal or anUCI signal (e.g., over the direct link 210-b), to activate or deactivatethe ability to redundancy feedback information to the transmitting UE115-a, for example based on channel conditions for sidelink connection220-a conditions or sidelink quality of service targets.

FIG. 4 illustrates an example of a wireless communications system 400that supports adaptive rateless coding for sidelink communications inaccordance with aspects of the present disclosure. Wirelesscommunications system 400 may implement aspects of or may be implementedby aspects of wireless communications systems 100 or 200. For example,wireless device 410-a may be a transmitting wireless devicecommunicating with one or more receiving wireless devices 415.Transmitting wireless device 410-a may be an example of any transmittingdevice, such as a base station 105 as described herein, a UE 115 asdescribed herein, or the like. Transmitting wireless device 410-a maycommunicate with receiving wireless device 415-a via communication link405-a, and with receiving wireless device 415-b via communication link405-b. The receiving wireless devices 415 may be, for example, UEs 115or base stations 105 as described herein. The communication links may beUu interfaces, PC5 interfaces, or the like.

The transmitting wireless device 410-a may encode and transmit controland data signaling to receiving wireless devices 415. In some examples,the transmitting wireless device 410-a may perform encoding (e.g.,fountain coding, such as network encoding) on k original symbols orsubpackets (e.g., where k=100) as described in greater detail withreference to FIG. 3 , where the k original symbols or subpacketscomprise a packet. In such examples, the transmitting wireless device410-a may send N encoded symbols or subpackets to a receiving wirelessdevice 415. Each receiving wireless device 415 may be associated withreceived M encoded symbols or subpackets (e.g., where M<N) to recoverthe original symbols or subpackets encoded by the transmitting wirelessdevice 410-a with a given probability. For a given performance target,in some examples, a decoding success probability M may be fixed (e.g.,M=120).

As described herein, different communication links may experiencedifferent channel conditions, resulting in different packet losses. Forinstance, communication link 405-a may experience packet lossprobability 1 (e.g., 0.1), while communication link 405-b may experiencepacket loss probability 2 (e.g., 0.2). To achieve a similar networkencoding performance for all receiving wireless devices (e.g., receivingwireless device 415-a and receiving wireless device 415-b), thetransmitting wireless device 410-a may construct receiver-specificredundancies for corresponding network coding transmissions, asdescribed herein. For example, for k=100 and M=120, a packet lossprobability 1 (e.g., 10%) means that about 12 packets or symbols of the120 packets or symbols may be lost. Thus, the transmitting wirelessdevice 410-a may select a redundancy configuration resulting in N=133for transmissions to receiving wireless device 415-a (e.g., 100 originalsymbols plus 20 to satisfy M=120 plus 13 to address packet lossprobability 1 for communication link 405-a). Thus, even with path loss1=0.1, if ten percent of the 120 encoded symbols decoded by thereceiving wireless device 415-a are lost, the added redundancy of 13encoded symbols may result in successful reception of the original oneor more encoded packets by the receiving wireless device 415-a.Similarly, the transmitting wireless device 410-a may select aredundancy configuration resulting in N=150 for transmissions toreceiving wireless device 415-b (e.g., 100 original symbols plus 20 tosatisfy M=120 plus 30 to address packet loss probability 2 for 220communication link 405-b).

For example, with reference to FIG. 2 , a sidelink connection 220-a mayhave different channel conditions than a direct link 210-a. For example,the direct link 210-a may experience a packet loss probability of 1,while the sidelink connection 220-a may experience a packet lossprobability of 2, as described with reference to FIG. 4 . Accordingly,the receiving UE 115-b may provide feedback (e.g., packet-levelfeedback) indicating a sufficiency of the amount of redundancy forencoding using the rateless encoding algorithm for the sidelinkconnection 220-a, as described in greater detail with reference to FIG.6 .

For example, a receiving UE 115-b may estimate a packet loss probabilityfor the sidelink connection 220-a. For instance, receiving UE 115-b maycalculate, or otherwise determine, a packet loss probability (e.g.,P_(1oss)) as a packet delivery rate over a given period of time (e.g.,T). The receiving UE 115-b may estimate a packet loss probability as anumber of received packets divided by a total number of packetstransmitted during time

$T{\left( {P_{loss} = \frac{{Number}{of}{Received}{Packets}}{{Total}{number}{of}{Transmitted}{Packets}}} \right).}$

An amount of redundancy for the transmission may be calculated asredundancy

$R = {\frac{M}{1 - P_{loss}} - {k.}}$

In some examples, the receiving UE 115-b may transmit a packet lossprobability report (e.g., including an indication of P_(loss)) to thetransmitting UE 115-a, and the transmitting UE 115-a may select (e.g.,calculate) an amount of redundancy (e.g., a value for R) and encodefuture packets for transmission to the receiving UE 115-b according tothe updated amount of redundancy. In some examples, the receiving UE115-b may calculate the amount of redundancy (e.g., value for R), andmay transmit an indication of a requested amount of redundancy to thetransmitting UE 115-a. In some examples, the redundancy may becalculated through a lookup table (LUT), which may map a given packetloss probability P_(loss) to a redundancy value R. In some examples, thebase station 105-a may transmit the lookup table to the receiving UE115-b and/or the transmitting UE 115-a, for example in a configurationmessage or via RRC. The receiving UE 115-b may map the calculatedP_(loss) to the corresponding R and transmit an indication (e.g., anindex corresponding to the LUT) of the corresponding R to the basestation 105-a. In some examples, the receiving UE 115-b may transmit anindication of a calculated P_(loss) to the transmitting UE 115-a and thetransmitting UE 115-a may map the indicated P_(loss) to a correspondingR via the LUT.

In some cases, the receiving UE 115-b may transmit, to the transmittingUE 115-a, redundancy feedback information that may include a request toincrease or decrease the amount of redundancy R, for example based onwhether the receiving UE 115-b successfully decoded a received packet.In some examples, the receiving UE 115-b may request the transmitting UE115-a to increase or decrease the amount of redundancy R by a givenamount (e.g., a step size A) based on whether the receiving UE 115-bsuccessfully decoded a received packet. In some cases, the receiving UE115-b may transmit, to the transmitting UE 115-a, redundancy feedbackinformation that may include a determination that decoding of a packetwas successful or unsuccessful. The transmitting UE 115-a may increaseor decrease the amount of redundancy R based on whether the packet wassuccessfully decoded. In some examples, the transmitting UE 115-a mayincrease or decrease the amount of redundancy R by a given amount (e.g.,a step size A) based on whether the packet was successfully decoded.

FIG. 5 illustrates an example of a protocol stack diagram 500 thatsupports adaptive rateless coding for sidelink communications inaccordance with aspects of the present disclosure. Protocol stackdiagram 500 may implement aspects of or may be implemented by aspects ofwireless communications systems 100 or 200. For example, UEs 115-d and115-e may be examples of a UE 115 as described herein.

A transmitting UE 115-d may include a packet data convergence protocolservice data unit (PDCP SDU) 505 and a receiving UE 115-e may include apacket data convergence protocol (PDCP) protocol data unit (PDU) 565.The PDCP SDU 505 and the PDCP PDU 565 may operate in the packet dataconvergence protocol (PDCP) layer.

When transmitting a network encoded packet, the transmitting UE 115-dmay divide an original data packet into a quantity k PDCP subpackets at510 within a network coding layer and encode the k PDCP subpackets usinga rateless encoding algorithm 515. At the radio link control (RLC)layer, at 520, the encoding algorithm generates a quantity N encodedsubpackets, where N is a greater number than k. The difference between Nand k corresponds to an amount of redundancy associated with therateless encoding algorithm 515. The N encoded subpackets are thenpassed to the MAC layer at 800 525 and transmitted across the airinterface in a MAC protocol data unit (MAC PDU) transport block at 530.

At the receiving UE 115-e, the receiving UE 115-e receives the MAC PDUtransport block at 535. The encoded subpackets in the MAC layer at 540are passed to the RLC layer at 545. The receiving UE 115-e may receive alesser quantity N′ of subpackets than the N subpackets that thetransmitting UE 115-d transmitted due to channel conditions (e.g., dueto pathloss on the sidelink channel). If N′ is greater than a number M(where M is less than N, but greater than k), then the receiving UE115-e may be able to recover the original k subpackets with a with adesired probability (e.g., 99%).

The N′ received encoded packets are passed through a decoding algorithm550 corresponding to the encoding algorithm 515 in the network codingsublayer. The decoding algorithm 550 outputs a number of decoded packets555 which are combined to form the original packet at the PDCP PDU 565.As discussed herein, the receiving UE 115-e may transmit feedbackinformation (e.g., packet-level feedback information) to thetransmitting UE 115-d regarding whether the receiving UE 115-esuccessfully decoded the packet or whether to increase or decrease theredundancy associated with the rateless coding algorithm.

FIG. 6 illustrates an example of a process flow 600 that supportsadaptive rateless coding for sidelink communications in accordance withaspects of the present disclosure. Process flow 600 may implementaspects of or may be implemented by aspects of wireless communicationssystems 100 or 200. For example, base station 105-b may be an example ofa base station 105 as described herein, and UEs 115-f and 115-g may beexamples of a UE 115 as described herein.

At 605, the base station 105-b may transmit, to the UEs 115-f and 115-g,signaling that indicates a first amount or redundancy to use forencoding using a rateless encoding algorithm (e.g., for a network codingprocedure). In some examples, the base station 105-b may also transmit,to the UEs 115-f and 115-g, one or more other parameters associated withthe rateless coding, for example a quantity of subpackets into which todivide each packet for encoding using the rateless encoding algorithm,an indication of the rateless encoding algorithm, an indication of arateless decoding algorithm, or an indication of a pool of transmissionresources for sidelink communications between the UEs 115-f and 115-g.

At 610, the transmitting UE 115-f, encodes a first packet using therateless encoding algorithm and in accordance with the first amount ofredundancy indicated by the base station 105-b, and transmits theencoded packet to the receiving UE 115-g. In some cases, encoding thefirst packet using the rateless encoding algorithm and in accordancewith the first amount of redundancy includes dividing the first packetinto a set of subpackets including a first quantity of subpackets, andgenerating a set of encoded subpackets based on the set of subpacketsand using the rateless encoding algorithm, where the set of encodedsubpackets includes a second quantity of encoded subpackets that isgreater than the first quantity of subpackets, and where the firstamount of redundancy for encoding using the rateless encoding algorithmis a difference between the second quantity of encoded subpackets andthe first quantity of subpackets.

At 615, the receiving UE 115-g decodes the first packet using a decodingalgorithm that corresponds to the encoding algorithm. In some cases,decoding the first packet using the rateless decoding algorithmincludes: identifying a set of encoded subpackets received for the firstpacket, the set of encoded subpackets including a first quantity ofencoded subpackets greater than or equal to a second quantity oforiginal subpackets encoded using the rateless encoding algorithm;decoding the set of encoded subpackets to obtain a set of decodedsubpackets including a third quantity of decoded subpackets, the thirdquantity greater than or equal to the second quantity; and attempting toobtain the first packet based at least in part on the set of decodedsubpackets.

At 620, the receiving UE 115-g transmits, to the transmitting UE 115-f,a message including information that indicates a sufficiency of thefirst amount of redundancy for encoding using the rateless encodingalgorithm based on the decoding of the first packet at 615. In somecases, at 620, the information that indicates a sufficiency of the firstamount of redundancy may be packet-level information, and thus may bebased on whether one or more entire packets (e.g., entire sets ofsub-packets, each entire set of sub-packets being the complete set ofsub-packets for a corresponding packet) was successfully decoded. Insome cases, the receiving UE 115-g may transmit, to the base station105-b, a request to transmit the information that indicates thesufficiency of the first amount of redundancy for encoding using therateless encoding algorithm. In response, the base station 105-b maytransmit a grant to the receiving UE 115-g. In some cases, the receivingUE 115-g may transmit the message including information that indicates asufficiency of the first amount of redundancy for encoding using therateless encoding algorithm based on receiving the grant. In some cases,the receiving UE 115-g may transmit, to the base station 105-b, therequest to transmit the information that indicates the sufficiency ofthe first amount of redundancy for encoding using the rateless encodingalgorithm based on a condition of the sidelink channel or a quality ofservice target associated with the sidelink channel. In some cases, thereceiving UE 115-g may receive, from the base station 105-b, a requestto transmit the information that indicates the sufficiency of the firstamount of redundancy for encoding using the rateless encoding algorithm,and the receiving UE 115-g may transmit the message comprising theinformation that indicates the sufficiency of the first amount ofredundancy for encoding using the rateless encoding algorithm based onthe request from the base station 105-b.

At 625, the transmitting UE 115-f determines a second amount ofredundancy for encoding using the rateless encoding algorithm based onthe feedback information received at 620.

Depending on whether the redundancy is sufficient or not, the messageincluding packet-level information that indicates a sufficiency of thefirst amount of redundancy may include a message that the first amountof redundancy is sufficient for encoding using the rateless encodingalgorithm, or, alternatively, the message may indicate that the firstamount of redundancy is insufficient for encoding using the ratelessencoding algorithm. Whether the amount of redundancy is sufficient orinsufficient may be communicated in various ways. In some cases, themessage including information that indicates a sufficiency of the firstamount of redundancy transmitted at 620 may include an estimated packetloss probability calculated by the receiving UE 115-g. For example, thereceiving UE 115-g may estimate the loss probability based ondetermining a first quantity of subpackets received by the receiving UE115-g during a time period and a second quantity of subpacketstransmitted by the transmitting UE 115-f during the time period, wherethe loss probability is based on a ratio between the first quantity ofsubpackets received by the receiving UE 115-g and the second quantity ofsubpackets transmitted by the transmitting UE 115-f during the timeperiod. At 625, the transmitting UE 115-f may determine the secondamount of redundancy based on the indicated packet loss probability(p_loss). For example, the transmitting UE 115-f may calculate thesecond amount of redundancy R as R=M/(1−p_loss)−k. In some examples, thetransmitting UE 115-f may calculate the second amount of redundancy Rthrough a lookup table, which may map a given packet loss probabilityP_(loss) to a redundancy value R. In some examples, the base station105-b may transmit the lookup table to the receiving UE 115-g and/or thetransmitting UE 115-f.

In some cases, the message including information that indicates asufficiency of the first amount of redundancy transmitted at 620 mayinclude a desired amount of redundancy. For example, the receiving UE115-g may calculate the packet loss probability (p_loss) and calculatethe desired amount of redundancy based on the packet loss probability(e.g., via determining R through R=M/(1−p_loss)−k or via a lookuptable). The transmitting UE 115-f may determine the second amount ofredundancy based on the indicated desired amount of redundancy.

In some cases, the message including information that indicates asufficiency of the first amount of redundancy transmitted at 620 mayinclude a request to increase or decrease the amount of redundancy R,for example, based on whether the receiving UE 115-g successfullydecoded the received packet. In some examples, the message includinginformation that indicates a sufficiency of the first amount ofredundancy transmitted at 620 may include a request increase or decreasethe amount of redundancy R by a given amount (e.g., a step size A), forexample, based on whether the receiving UE 115-g successfully decodedthe received packet.

In some cases, the message including information that indicates asufficiency of the first amount of redundancy transmitted at 620 mayinclude an indication that decoding of a packet was successful orunsuccessful. At 625, the transmitting UE 115-f may increase or decreasethe amount of redundancy R based on the indication at 620 of whether thepacket was successfully decoded. In some examples, the transmitting UE115-f may increase or decrease the amount of redundancy R by a givenamount (e.g., a step size A) based on the indication at 620 of whetherthe packet was successfully decoded.

In some cases, a message including information that indicates asufficiency of an amount of redundancy may include multiple types ofsuch information described herein (e.g., any type of information thatindicates a sufficiency of an amount of redundancy may be included in amessage in combination with any other type of information that indicatesa sufficiency of an amount of redundancy). For example, a message thatincludes information that indicates a sufficiency of an amount ofredundancy may include any combination of one or more of informationthat indicates a different amount of redundancy, a request to decreasethe amount of redundancy, a request to increase the amount ofredundancy, an indication of whether a packet was successfully decoded,or any combination thereof.

At 630, the transmitting UE 115-f encodes a second packet using therateless encoding algorithm and in accordance with the determined secondamount of redundancy, and transmits the encoded packet to the receivingUE 115-g. At 635, the receiving UE 115-g decodes the second packet usingthe decoding algorithm that corresponds to the encoding algorithm.

At 640, the receiving UE 115-g transmits, to the transmitting UE 115-f,a message including information that indicates a sufficiency of thesecond amount of redundancy for encoding using the rateless encodingalgorithm based on the decoding of the second packet at 635. Theinformation that indicates the sufficiency of the second amount ofredundancy may be packet-level information. The information thatindicates the sufficiency of the second amount of redundancy may bepacket-level information also may indicate that the second amount ofredundancy is sufficient or, alternatively, insufficient.

In some cases, the transmitting UE 115-f will return to 625 anddetermine an updated amount of redundancy based on the redundancyfeedback received at 640. In some cases, if receiving UE 115-g indicatesthat it continues to fail to successfully decode the packet, at 645, thetransmitting UE 115-f may transmit, to the base station 105-b, a requestto switch from using the rateless encoding algorithm to using adifferent rateless encoding algorithm. In response, at 650, the basestation 105-b may transmit an indication of a second rateless encodingalgorithm to the transmitting UE 115-f and an indication of acorresponding second rateless decoding algorithm to the receiving UE115-g. The transmitting UE 115-f may encode, and the receiving UE 115-gmay decode, future packets based on the received second ratelessencoding and second rateless decoding algorithms.

FIG. 7 shows a block diagram 700 of a device 705 that supports adaptiverateless coding for sidelink communications in accordance with aspectsof the present disclosure. The device 705 may be an example of aspectsof a UE 115 as described herein. The device 705 may include a receiver710, a transmitter 715, and a communications manager 720. The device 705may also include a processor. Each of these components may be incommunication with one another (e.g., via one or more buses).

The receiver 710 may provide a means for receiving information such aspackets, user data, control information, or any combination thereofassociated with various information channels (e.g., control channels,data channels, information channels related to adaptive network codingfor sidelink communications). Information may be passed on to othercomponents of the device 705. The receiver 710 may utilize a singleantenna or a set of multiple antennas.

The transmitter 715 may provide a means for transmitting signalsgenerated by other components of the device 705. For example, thetransmitter 715 may transmit information such as packets, user data,control information, or any combination thereof associated with variousinformation channels (e.g., control channels, data channels, informationchannels related to adaptive rateless coding for sidelinkcommunications). In some examples, the transmitter 715 may be co-locatedwith a receiver 710 in a transceiver module. The transmitter 715 mayutilize a single antenna or a set of multiple antennas.

The communications manager 720, the receiver 710, the transmitter 715,or various combinations thereof or various components thereof may beexamples of means for performing various aspects of adaptive ratelesscoding for sidelink communications as described herein. For example, thecommunications manager 720, the receiver 710, the transmitter 715, orvarious combinations or components thereof may support a method forperforming one or more of the functions described herein.

In some examples, the communications manager 720, the receiver 710, thetransmitter 715, or various combinations or components thereof may beimplemented in hardware (e.g., in communications management circuitry).The hardware may include a processor, a digital signal processor (DSP),an application-specific integrated circuit (ASIC), a field-programmablegate array (FPGA) or other programmable logic device, a discrete gate ortransistor logic, discrete hardware components, or any combinationthereof configured as or otherwise supporting a means for performing thefunctions described in the present disclosure. In some examples, aprocessor and memory coupled with the processor may be configured toperform one or more of the functions described herein (e.g., byexecuting, by the processor, instructions stored in the memory).

Additionally or alternatively, in some examples, the communicationsmanager 720, the receiver 710, the transmitter 715, or variouscombinations or components thereof may be implemented in code (e.g., ascommunications management software or firmware) executed by a processor.If implemented in code executed by a processor, the functions of thecommunications manager 720, the receiver 710, the transmitter 715, orvarious combinations or components thereof may be performed by ageneral-purpose processor, a DSP, a central processing unit (CPU), anASIC, an FPGA, or any combination of these or other programmable logicdevices (e.g., configured as or otherwise supporting a means forperforming the functions described in the present disclosure).

In some examples, the communications manager 720 may be configured toperform various operations (e.g., receiving, monitoring, transmitting)using or otherwise in cooperation with the receiver 710, the transmitter715, or both. For example, the communications manager 720 may receiveinformation from the receiver 710, send information to the transmitter715, or be integrated in combination with the receiver 710, thetransmitter 715, or both to receive information, transmit information,or perform various other operations as described herein.

The communications manager 720 may support wireless communications at afirst UE in accordance with examples as disclosed herein. For example,the communications manager 720 may be configured as or otherwise supporta means for receiving, from a base station, signaling that indicates afirst amount of redundancy for encoding using a rateless encodingalgorithm. The communications manager 720 may be configured as orotherwise support a means for encoding a first packet using the ratelessencoding algorithm and in accordance with the first amount of redundancyto obtain an encoded first packet. The communications manager 720 may beconfigured as or otherwise support a means for transmitting the encodedfirst packet to a second UE via a sidelink channel. The communicationsmanager 720 may be configured as or otherwise support a means forreceiving, from the second UE, a message including information (e.g.,packet-level information) that indicates a sufficiency of the firstamount of redundancy for encoding using the rateless encoding algorithm.The communications manager 720 may be configured as or otherwise supporta means for encoding a second packet using the rateless encodingalgorithm and in accordance with a second amount of redundancy to obtainan encoded second packet, the second amount of redundancy different thanthe first amount of redundancy and based on the sufficiency of the firstamount of redundancy for encoding using the rateless encoding algorithm.The communications manager 720 may be configured as or otherwise supporta means for transmitting the encoded second packet to the second UE viathe sidelink channel.

Additionally or alternatively, the communications manager 720 maysupport wireless communications at a second UE in accordance withexamples as disclosed herein. For example, the communications manager720 may be configured as or otherwise support a means for receiving,from a base station, signaling that indicates a first amount ofredundancy for encoding using a rateless encoding algorithm. Thecommunications manager 720 may be configured as or otherwise support ameans for receiving, from a first UE via a sidelink channel, a packetencoded using the rateless encoding algorithm and in accordance with thefirst amount of redundancy. The communications manager 720 may beconfigured as or otherwise support a means for decoding the packet usinga rateless decoding algorithm that corresponds to the rateless encodingalgorithm. The communications manager 720 may be configured as orotherwise support a means for transmitting, to the first UE based ondecoding the packet using the rateless decoding algorithm, a messageincluding information (e.g., packet-level information) that indicates asufficiency of the first amount of redundancy for encoding using therateless encoding algorithm.

By including or configuring the communications manager 720 in accordancewith examples as described herein, the device 705 (e.g., a processorcontrolling or otherwise coupled to the receiver 710, the transmitter715, the communications manager 720, or a combination thereof) maysupport techniques for may support techniques for more efficientutilization of communication resources, which may results in moreefficient encoding and decoding of packets.

FIG. 8 shows a block diagram 800 of a device 805 that supports adaptiverateless coding for sidelink communications in accordance with aspectsof the present disclosure. The device 805 may be an example of aspectsof a device 705 or a UE 115 as described herein. The device 805 mayinclude a receiver 810, a transmitter 815, and a communications manager820. The device 805 may also include a processor. Each of thesecomponents may be in communication with one another (e.g., via one ormore buses).

The receiver 810 may provide a means for receiving information such aspackets, user data, control information, or any combination thereofassociated with various information channels (e.g., control channels,data channels, information channels related to adaptive rateless codingfor sidelink communications). Information may be passed on to othercomponents of the device 805. The receiver 810 may utilize a singleantenna or a set of multiple antennas.

The transmitter 815 may provide a means for transmitting signalsgenerated by other components of the device 805. For example, thetransmitter 815 may transmit information such as packets, user data,control information, or any combination thereof associated with variousinformation channels (e.g., control channels, data channels, informationchannels related to adaptive rateless coding for sidelinkcommunications). In some examples, the transmitter 815 may be co-locatedwith a receiver 810 in a transceiver module. The transmitter 815 mayutilize a single antenna or a set of multiple antennas.

The device 805, or various components thereof, may be an example ofmeans for performing various aspects of adaptive rateless coding forsidelink communications as described herein. For example, thecommunications manager 820 may include a direct link manager 825, apacket encoder 830, a sidelink message transmitter 835, a sidelinkfeedback receiver 840, a sidelink message receiver 845, a packet decoder850, a sidelink feedback transmitter 855, or any combination thereof.The communications manager 820 may be an example of aspects of acommunications manager 720 as described herein. In some examples, thecommunications manager 820, or various components thereof, may beconfigured to perform various operations (e.g., receiving, monitoring,transmitting) using or otherwise in cooperation with the receiver 810,the transmitter 815, or both. For example, the communications manager820 may receive information from the receiver 810, send information tothe transmitter 815, or be integrated in combination with the receiver810, the transmitter 815, or both to receive information, transmitinformation, or perform various other operations as described herein.

The communications manager 820 may support wireless communications at afirst UE in accordance with examples as disclosed herein. The directlink manager 825 may be configured as or otherwise support a means forreceiving, from a base station, signaling that indicates a first amountof redundancy for encoding using a rateless encoding algorithm. Thepacket encoder 830 may be configured as or otherwise support a means forencoding a first packet using the rateless encoding algorithm and inaccordance with the first amount of redundancy to obtain an encodedfirst packet. The sidelink message transmitter 835 may be configured asor otherwise support a means for transmitting the encoded first packetto a second UE via a sidelink channel. The sidelink feedback receiver840 may be configured as or otherwise support a means for receiving,from the second UE, a message including information (e.g., packet-levelinformation) that indicates a sufficiency of the first amount ofredundancy for encoding using the rateless encoding algorithm. Thepacket encoder 830 may be configured as or otherwise support a means forencoding a second packet using the rateless encoding algorithm and inaccordance with a second amount of redundancy to obtain an encodedsecond packet, the second amount of redundancy different than the firstamount of redundancy and based on the sufficiency of the first amount ofredundancy for encoding using the rateless encoding algorithm. Thesidelink message transmitter 835 may be configured as or otherwisesupport a means for transmitting the encoded second packet to the secondUE via the sidelink channel.

Additionally or alternatively, the communications manager 820 maysupport wireless communications at a second UE in accordance withexamples as disclosed herein. The direct link manager 825 may beconfigured as or otherwise support a means for receiving, from a basestation, signaling that indicates a first amount of redundancy forencoding using a rateless encoding algorithm. The sidelink messagereceiver 845 may be configured as or otherwise support a means forreceiving, from a first UE via a sidelink channel, a packet encodedusing the rateless encoding algorithm and in accordance with the firstamount of redundancy. The packet decoder 850 may be configured as orotherwise support a means for decoding the packet using a ratelessdecoding algorithm that corresponds to the rateless encoding algorithm.The sidelink feedback transmitter 855 may be configured as or otherwisesupport a means for transmitting, to the first UE based on decoding thepacket using the rateless decoding algorithm, a message includinginformation (packet-level information) that indicates a sufficiency ofthe first amount of redundancy for encoding using the rateless encodingalgorithm.

FIG. 9 shows a block diagram 900 of a communications manager 920 thatsupports adaptive rateless coding for sidelink communications inaccordance with aspects of the present disclosure. The communicationsmanager 920 may be an example of aspects of a communications manager720, a communications manager 820, or both, as described herein. Thecommunications manager 920, or various components thereof, may be anexample of means for performing various aspects of adaptive ratelesscoding for sidelink communications as described herein. For example, thecommunications manager 920 may include a direct link manager 925, apacket encoder 930, a sidelink message transmitter 935, a sidelinkfeedback receiver 940, a sidelink message receiver 945, a packet decoder950, a sidelink feedback transmitter 955, a redundancy manager 960, aloss probability estimator 965, or any combination thereof. Each ofthese components may communicate, directly or indirectly, with oneanother (e.g., via one or more buses).

The communications manager 920 may support wireless communications at afirst UE in accordance with examples as disclosed herein. The directlink manager 925 may be configured as or otherwise support a means forreceiving, from a base station, signaling that indicates a first amountof redundancy for encoding using a rateless encoding algorithm. Thepacket encoder 930 may be configured as or otherwise support a means forencoding a first packet using the rateless encoding algorithm and inaccordance with the first amount of redundancy to obtain an encodedfirst packet. The sidelink message transmitter 935 may be configured asor otherwise support a means for transmitting the encoded first packetto a second UE via a sidelink channel. The sidelink feedback receiver940 may be configured as or otherwise support a means for receiving,from the second UE, a message including information (e.g., packet-levelinformation) that indicates a sufficiency of the first amount ofredundancy for encoding using the rateless encoding algorithm. In someexamples, the packet encoder 930 may be configured as or otherwisesupport a means for encoding a second packet using the rateless encodingalgorithm and in accordance with a second amount of redundancy to obtainan encoded second packet, the second amount of redundancy different thanthe first amount of redundancy and based on the sufficiency of the firstamount of redundancy for encoding using the rateless encoding algorithm.In some examples, the sidelink message transmitter 935 may be configuredas or otherwise support a means for transmitting the encoded secondpacket to the second UE via the sidelink channel.

In some examples, the information that indicates the sufficiency of thefirst amount of redundancy indicates an estimated loss probability forthe first packet, and the redundancy manager 960 may be configured as orotherwise support a means for determining the second amount ofredundancy based on the estimated loss probability.

In some examples, to support determining the second amount of redundancybased on the estimated loss probability, the redundancy manager 960 maybe configured as or otherwise support a means for identifying the secondamount of redundancy based on an index value for a lookup table, wherethe index value for the lookup table corresponds to the estimated lossprobability.

In some examples, to support receiving the message including theinformation that indicates the sufficiency of the first amount ofredundancy, the sidelink feedback receiver 940 may be configured as orotherwise support a means for receiving, in the message, an indicationof the second amount of redundancy.

In some examples, to support receiving the message including theinformation that indicates the sufficiency of the first amount ofredundancy, the sidelink feedback receiver 940 may be configured as orotherwise support a means for receiving, in the message, a request todecrease an amount of redundancy for encoding using the ratelessencoding algorithm, where the second amount of redundancy is less thanthe first amount of redundancy.

In some examples, to support receiving the message including theinformation that indicates the sufficiency of the first amount ofredundancy, the sidelink feedback receiver 940 may be configured as orotherwise support a means for receiving, in the message, a request toincrease an amount of redundancy for encoding using the ratelessencoding algorithm, where the second amount of redundancy is greaterthan the first amount of redundancy.

In some examples, to support receiving the message including theinformation that indicates the sufficiency of the first amount ofredundancy, the sidelink feedback receiver 940 may be configured as orotherwise support a means for receiving, in the message, an indicationof whether the first packet was successfully decoded, where the secondamount of redundancy is based on the indication.

In some examples, to support encoding the first packet using therateless encoding algorithm, the packet encoder 930 may be configured asor otherwise support a means for dividing the first packet into a set ofsubpackets including a first quantity of subpackets. In some examples,to support encoding the first packet using the rateless encodingalgorithm, the packet encoder 930 may be configured as or otherwisesupport a means for generating a set of encoded subpackets based on theset of subpackets and using the rateless encoding algorithm, where theset of encoded subpackets includes a second quantity of encodedsubpackets that is greater than the first quantity of subpackets, andwhere an amount of redundancy for encoding using the rateless encodingalgorithm includes a difference between the second quantity of encodedsubpackets and the first quantity of subpackets.

In some examples, the sidelink feedback receiver 940 may be configuredas or otherwise support a means for receiving, from the second UE, asecond message including information (e.g., packet-level information)that indicates a second sufficiency of the second amount of redundancyfor encoding using the rateless encoding algorithm. In some examples,the direct link manager 925 may be configured as or otherwise support ameans for transmitting, to the base station and based on the informationthat indicates the second sufficiency of the second amount of redundancyfor encoding using the rateless encoding algorithm, a request to switchfrom using the rateless encoding algorithm to using a different ratelessencoding algorithm for sidelink communications. In some examples, thedirect link manager 925 may be configured as or otherwise support ameans for receiving, from the base station, an indication of a secondrateless encoding algorithm that includes the different ratelessencoding algorithm. In some examples, the packet encoder 930 may beconfigured as or otherwise support a means for encoding a third packetusing the second rateless encoding algorithm to obtain an encoded thirdpacket. In some examples, the sidelink message transmitter 935 may beconfigured as or otherwise support a means for transmitting the encodedthird packet to the second UE via the sidelink channel.

In some examples, the direct link manager 925 may be configured as orotherwise support a means for receiving an indication of a quantity ofsubpackets into which to divide each packet for encoding using therateless encoding algorithm, an indication of the rateless encodingalgorithm, an indication of a rateless decoding algorithm, an indicationof a pool of transmission resources for sidelink communications by thefirst UE, or any combination thereof.

Additionally or alternatively, the communications manager 920 maysupport wireless communications at a second UE in accordance withexamples as disclosed herein. In some examples, the direct link manager925 may be configured as or otherwise support a means for receiving,from a base station, signaling that indicates a first amount ofredundancy for encoding using a rateless encoding algorithm. Thesidelink message receiver 945 may be configured as or otherwise supporta means for receiving, from a first UE via a sidelink channel, a packetencoded using the rateless encoding algorithm and in accordance with thefirst amount of redundancy. The packet decoder 950 may be configured asor otherwise support a means for decoding the packet using a ratelessdecoding algorithm that corresponds to the rateless encoding algorithm.The sidelink feedback transmitter 955 may be configured as or otherwisesupport a means for transmitting, to the first UE based on decoding thepacket using the rateless decoding algorithm, a message includinginformation (e.g., packet-level information) that indicates asufficiency of the first amount of redundancy for encoding using therateless encoding algorithm.

In some examples, the loss probability estimator 965 may be configuredas or otherwise support a means for estimating a loss probability forthe packet, where the information that indicates the sufficiency of thefirst amount of redundancy for encoding using the rateless encodingalgorithm indicates the estimated loss probability for the packet.

In some examples, to support estimating the loss probability for thepacket, the loss probability estimator 965 may be configured as orotherwise support a means for determining a first quantity of subpacketsreceived by the second UE during a time period and a second quantity ofsubpackets transmitted by the first UE during the time period, the lossprobability based on a ratio between the first quantity of subpacketsreceived by the second UE and the second quantity of subpacketstransmitted by the first UE during the time period.

In some examples, the loss probability estimator 965 may be configuredas or otherwise support a means for estimating a loss probability forthe packet. In some examples, the redundancy manager 960 may beconfigured as or otherwise support a means for determining a secondamount of redundancy based on the estimated loss probability for thepacket, where the information that indicates the sufficiency of thefirst amount of redundancy for encoding using the rateless encodingalgorithm indicates the second amount of redundancy.

In some examples, to support determining the second amount of redundancybased on the estimated loss probability, the redundancy manager 960 maybe configured as or otherwise support a means for identifying the secondamount of redundancy based on an index value for a lookup table, wherethe index value for the lookup table corresponds to the estimated lossprobability.

In some examples, to support transmitting the message including theinformation that indicates the sufficiency of the first amount ofredundancy, the sidelink feedback transmitter 955 may be configured asor otherwise support a means for transmitting, in the message, a requestto increase an amount of redundancy.

In some examples, to support transmitting the message including theinformation that indicates the sufficiency of the first amount ofredundancy, the sidelink feedback transmitter 955 may be configured asor otherwise support a means for transmitting, in the message, a requestto decrease an amount of redundancy.

In some examples, to support transmitting the message including theinformation that indicates the sufficiency of the first amount ofredundancy, the sidelink feedback transmitter 955 may be configured asor otherwise support a means for transmitting, in the message, anindication of whether the packet was successfully decoded.

In some examples, to support decoding the packet using the ratelessdecoding algorithm, the packet decoder 950 may be configured as orotherwise support a means for identifying a set of encoded subpacketsreceived for the packet, the set of encoded subpackets including a firstquantity of encoded subpackets greater than or equal to a secondquantity of original subpackets encoded using the rateless encodingalgorithm. In some examples, to support decoding the packet using therateless decoding algorithm, the packet decoder 950 may be configured asor otherwise support a means for decoding the set of encoded subpacketsto obtain a set of decoded subpackets including a third quantity ofdecoded subpackets, the third quantity greater than or equal to thesecond quantity. In some examples, to support decoding the packet usingthe rateless decoding algorithm, the packet decoder 950 may beconfigured as or otherwise support a means for attempting to obtain thepacket based on the set of decoded subpackets.

In some examples, a probability of success for decoding the packet usingthe rateless decoding algorithm is based on a difference between thefirst quantity of encoded subpackets and the second quantity of originalsubpackets.

In some examples, the direct link manager 925 may be configured as orotherwise support a means for transmitting, to the base station, arequest to transmit the information that indicates the sufficiency ofthe first amount of redundancy for encoding using the rateless encodingalgorithm. In some examples, the direct link manager 925 may beconfigured as or otherwise support a means for receiving, from the basestation, a grant in response to the request, where the message includingthe information that indicates the sufficiency of the first amount ofredundancy for encoding using the rateless encoding algorithm istransmitted based on the grant from the base station.

In some examples, transmitting the request to transmit the informationthat indicates the sufficiency of the first amount of redundancy forencoding using the rateless encoding algorithm is based on one of acondition of the sidelink channel or a quality of service targetassociated with the sidelink channel.

In some examples, the direct link manager 925 may be configured as orotherwise support a means for receiving, from the base station, arequest to transmit the information that indicates the sufficiency ofthe first amount of redundancy for encoding using the rateless encodingalgorithm, where transmitting the message including the information thatindicates the sufficiency of the first amount of redundancy for encodingusing the rateless encoding algorithm is transmitted based on therequest from the base station.

In some examples, the sidelink message receiver 945 may be configured asor otherwise support a means for receiving, from the first UE via thesidelink channel, a second packet encoded using the rateless encodingalgorithm and in accordance with a second amount of redundancy differentthan the first amount of redundancy, the second amount of redundancydifferent than the first amount of redundancy and based on thesufficiency of the first amount of redundancy for encoding using therateless encoding algorithm.

In some examples, the direct link manager 925 may be configured as orotherwise support a means for receiving an indication of a quantity oforiginal subpackets for the packet encoded using the rateless encodingalgorithm, an indication of the rateless encoding algorithm, anindication of the rateless decoding algorithm, an indication of a poolof transmission resources for sidelink communications by the second UE,or any combination thereof.

FIG. 10 shows a diagram of a system 1000 including a device 1005 thatsupports adaptive rateless coding for sidelink communications inaccordance with aspects of the present disclosure. The device 1005 maybe an example of or include the components of a device 705, a device805, or a UE 115 as described herein. The device 1005 may communicatewirelessly with one or more base stations 105, UEs 115, or anycombination thereof. The device 1005 may include components forbi-directional voice and data communications including components fortransmitting and receiving communications, such as a communicationsmanager 1020, an input/output (I/O) controller 1010, a transceiver 1015,an antenna 1025, a memory 1030, code 1035, and a processor 1040. Thesecomponents may be in electronic communication or otherwise coupled(e.g., operatively, communicatively, functionally, electronically,electrically) via one or more buses (e.g., a bus 1045).

The I/O controller 1010 may manage input and output signals for thedevice 1005. The I/O controller 1010 may also manage peripherals notintegrated into the device 1005. In some cases, the I/O controller 1010may represent a physical connection or port to an external peripheral.In some cases, the I/O controller 1010 may utilize an operating systemsuch as iOS®, ANDROID®, MS-DOS®, MS-WINDOWS®, OS/2®, UNIX®, LINUX®, oranother known operating system. Additionally or alternatively, the I/Ocontroller 1010 may represent or interact with a modem, a keyboard, amouse, a touchscreen, or a similar device. In some cases, the I/Ocontroller 1010 may be implemented as part of a processor, such as theprocessor 1040. In some cases, a user may interact with the device 1005via the I/O controller 1010 or via hardware components controlled by theI/O controller 1010.

In some cases, the device 1005 may include a single antenna 1025.However, in some other cases, the device 1005 may have more than oneantenna 1025, which may be capable of concurrently transmitting orreceiving multiple wireless transmissions. The transceiver 1015 maycommunicate bi-directionally, via the one or more antennas 1025, wired,or wireless links as described herein. For example, the transceiver 1015may represent a wireless transceiver and may communicatebi-directionally with another wireless transceiver. The transceiver 1015may also include a modem to modulate the packets, to provide themodulated packets to one or more antennas 1025 for transmission, and todemodulate packets received from the one or more antennas 1025. Thetransceiver 1015, or the transceiver 1015 and one or more antennas 1025,may be an example of a transmitter 715, a transmitter 815, a receiver710, a receiver 810, or any combination thereof or component thereof, asdescribed herein.

The memory 1030 may include random access memory (RAM) and read-onlymemory (ROM). The memory 1030 may store computer-readable,computer-executable code 1035 including instructions that, when executedby the processor 1040, cause the device 1005 to perform variousfunctions described herein. The code 1035 may be stored in anon-transitory computer-readable medium such as system memory or anothertype of memory. In some cases, the code 1035 may not be directlyexecutable by the processor 1040 but may cause a computer (e.g., whencompiled and executed) to perform functions described herein. In somecases, the memory 1030 may contain, among other things, a basic I/Osystem (BIOS) which may control basic hardware or software operationsuch as the interaction with peripheral components or devices.

The processor 1040 may include an intelligent hardware device (e.g., ageneral-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, anFPGA, a programmable logic device, a discrete gate or transistor logiccomponent, a discrete hardware component, or any combination thereof).In some cases, the processor 1040 may be configured to operate a memoryarray using a memory controller. In some other cases, a memorycontroller may be integrated into the processor 1040. The processor 1040may be configured to execute computer-readable instructions stored in amemory (e.g., the memory 1030) to cause the device 1005 to performvarious functions (e.g., functions or tasks supporting adaptive ratelesscoding for sidelink communications). For example, the device 1005 or acomponent of the device 1005 may include a processor 1040 and memory1030 coupled to the processor 1040, the processor 1040 and memory 1030configured to perform various functions described herein.

The communications manager 1020 may support wireless communications at afirst UE in accordance with examples as disclosed herein. For example,the communications manager 1020 may be configured as or otherwisesupport a means for receiving, from a base station, signaling thatindicates a first amount of redundancy for encoding using a ratelessencoding algorithm. The communications manager 1020 may be configured asor otherwise support a means for encoding a first packet using therateless encoding algorithm and in accordance with the first amount ofredundancy to obtain an encoded first packet. The communications manager1020 may be configured as or otherwise support a means for transmittingthe encoded first packet to a second UE via a sidelink channel. Thecommunications manager 1020 may be configured as or otherwise support ameans for receiving, from the second UE, a message including information(e.g., packet-level information) that indicates a sufficiency of thefirst amount of redundancy for encoding using the rateless encodingalgorithm. The communications manager 1020 may be configured as orotherwise support a means for encoding a second packet using therateless encoding algorithm and in accordance with a second amount ofredundancy to obtain an encoded second packet, the second amount ofredundancy different than the first amount of redundancy and based onthe sufficiency of the first amount of redundancy for encoding using therateless encoding algorithm. The communications manager 1020 may beconfigured as or otherwise support a means for transmitting the encodedsecond packet to the second UE via the sidelink channel.

Additionally or alternatively, the communications manager 1020 maysupport wireless communications at a second UE in accordance withexamples as disclosed herein. For example, the communications manager1020 may be configured as or otherwise support a means for receiving,from a base station, signaling that indicates a first amount ofredundancy for encoding using a rateless encoding algorithm. Thecommunications manager 1020 may be configured as or otherwise support ameans for receiving, from a first UE via a sidelink channel, a packetencoded using the rateless encoding algorithm and in accordance with thefirst amount of redundancy. The communications manager 1020 may beconfigured as or otherwise support a means for decoding the packet usinga rateless decoding algorithm that corresponds to the rateless encodingalgorithm. The communications manager 1020 may be configured as orotherwise support a means for transmitting, to the first UE based ondecoding the packet using the rateless decoding algorithm, a messageincluding information (e.g., packet-level information) that indicates asufficiency of the first amount of redundancy for encoding using therateless encoding algorithm.

By including or configuring the communications manager 1020 inaccordance with examples as described herein, the device 1005 maysupport techniques for may support techniques for improved communicationreliability and more efficient utilization of communication resources,for example by reducing packet loss and reducing excess redundancy.

In some examples, the communications manager 1020 may be configured toperform various operations (e.g., receiving, monitoring, transmitting)using or otherwise in cooperation with the transceiver 1015, the one ormore antennas 1025, or any combination thereof. For example, thecommunications manager 1020 may be configured to receive or transmitmessages or other signaling as described herein via the transceiver1015. Although the communications manager 1020 is illustrated as aseparate component, in some examples, one or more functions describedwith reference to the communications manager 1020 may be supported by orperformed by the processor 1040, the memory 1030, the code 1035, or anycombination thereof. For example, the code 1035 may include instructionsexecutable by the processor 1040 to cause the device 1005 to performvarious aspects of adaptive rateless coding for sidelink communicationsas described herein, or the processor 1040 and the memory 1030 may beotherwise configured to perform or support such operations.

FIG. 11 shows a flowchart illustrating a method 1100 that supportsadaptive rateless coding for sidelink communications in accordance withaspects of the present disclosure. The operations of the method 1100 maybe implemented by a UE or its components as described herein. Forexample, the operations of the method 1100 may be performed by a UE 115as described with reference to FIGS. 1 through 10 . In some examples, aUE may execute a set of instructions to control the functional elementsof the UE to perform the described functions. Additionally oralternatively, the UE may perform aspects of the described functionsusing special-purpose hardware.

At 1105, the method may include receiving, from a base station,signaling that indicates a first amount of redundancy for encoding usinga rateless encoding algorithm. The operations of 1105 may be performedin accordance with examples as disclosed herein. In some examples,aspects of the operations of 1105 may be performed by a direct linkmanager 925 as described with reference to FIG. 9 . Additionally oralternatively, means for performing 1105 may, but not necessarily,include, for example, antenna 1025, transceiver 1015, communicationsmanager 1020, memory 1030 (including code 1035), processor 1040 and/orbus 1045.

At 1110, the method may include encoding a first packet using therateless encoding algorithm and in accordance with the first amount ofredundancy to obtain an encoded first packet. The operations of 1110 maybe performed in accordance with examples as disclosed herein. In someexamples, aspects of the operations of 1110 may be performed by a packetencoder 930 as described with reference to FIG. 9 . Additionally oralternatively, means for performing 1110 may, but not necessarily,include, for example, antenna 1025, transceiver 1015, communicationsmanager 1020, memory 1030 (including code 1035), processor 1040 and/orbus 1045.

At 1115, the method may include transmitting the encoded first packet toa second UE via a sidelink channel. The operations of 1115 may beperformed in accordance with examples as disclosed herein. In someexamples, aspects of the operations of 1115 may be performed by asidelink message transmitter 935 as described with reference to FIG. 9 .Additionally or alternatively, means for performing 1115 may, but notnecessarily, include, for example, antenna 1025, transceiver 1015,communications manager 1020, memory 1030 (including code 1035),processor 1040 and/or bus 1045.

At 1120, the method may include receiving, from the second UE, a messageincluding packet-level information that indicates a sufficiency of thefirst amount of redundancy for encoding using the rateless encodingalgorithm. The message may indicate that the first amount of redundancyis sufficient for encoding using the rateless encoding algorithm, or,alternatively, the message may indicate that the first amount ofredundancy is insufficient for encoding using the rateless encodingalgorithm, as discussed above. The operations of 1120 may be performedin accordance with examples as disclosed herein. In some examples,aspects of the operations of 1120 may be performed by a sidelinkfeedback receiver 940 as described with reference to FIG. 9 .Additionally or alternatively, means for performing 1120 may, but notnecessarily, include, for example, antenna 1025, transceiver 1015,communications manager 1020, memory 1030 (including code 1035),processor 1040 and/or bus 1045.

At 1125, the method may include encoding a second packet using therateless encoding algorithm and in accordance with a second amount ofredundancy to obtain an encoded second packet, the second amount ofredundancy different than the first amount of redundancy and based onthe sufficiency of the first amount of redundancy for encoding using therateless encoding algorithm. The operations of 1125 may be performed inaccordance with examples as disclosed herein. In some examples, aspectsof the operations of 1125 may be performed by a packet encoder 930 asdescribed with reference to FIG. 9 . Additionally or alternatively,means for performing 1125 may, but not necessarily, include, forexample, antenna 1025, transceiver 1015, communications manager 1020,memory 1030 (including code 1035), processor 1040 and/or bus 1045.

At 1130, the method may include transmitting the encoded second packetto the second UE via the sidelink channel. The operations of 1130 may beperformed in accordance with examples as disclosed herein. In someexamples, aspects of the operations of 1130 may be performed by asidelink message transmitter 935 as described with reference to FIG. 9 .Additionally or alternatively, means for performing 1130 may, but notnecessarily, include, for example, antenna 1025, transceiver 1015,communications manager 1020, memory 1030 (including code 1035),processor 1040 and/or bus 1045.

FIG. 12 shows a flowchart illustrating a method 1200 that supportsadaptive rateless coding for sidelink communications in accordance withaspects of the present disclosure. The operations of the method 1200 maybe implemented by a UE or its components as described herein. Forexample, the operations of the method 1200 may be performed by a UE 115as described with reference to FIGS. 1 through 10 . In some examples, aUE may execute a set of instructions to control the functional elementsof the UE to perform the described functions. Additionally oralternatively, the UE may perform aspects of the described functionsusing special-purpose hardware.

At 1205, the method may include receiving, from a base station,signaling that indicates a first amount of redundancy for encoding usinga rateless encoding algorithm. The operations of 1205 may be performedin accordance with examples as disclosed herein. In some examples,aspects of the operations of 1205 may be performed by a direct linkmanager 925 as described with reference to FIG. 9 . Additionally oralternatively, means for performing 1205 may, but not necessarily,include, for example, antenna 1025, transceiver 1015, communicationsmanager 1020, memory 1030 (including code 1035), processor 1040 and/orbus 1045.

At 1210, the method may include encoding a first packet using therateless encoding algorithm and in accordance with the first amount ofredundancy to obtain an encoded first packet. The operations of 1210 maybe performed in accordance with examples as disclosed herein. In someexamples, aspects of the operations of 1210 may be performed by a packetencoder 930 as described with reference to FIG. 9 . Additionally oralternatively, means for performing 1210 may, but not necessarily,include, for example, antenna 1025, transceiver 1015, communicationsmanager 1020, memory 1030 (including code 1035), processor 1040 and/orbus 1045.

At 1215, the method may include transmitting the encoded first packet toa second UE via a sidelink channel. The operations of 1215 may beperformed in accordance with examples as disclosed herein. In someexamples, aspects of the operations of 1215 may be performed by asidelink message transmitter 935 as described with reference to FIG. 9 .Additionally or alternatively, means for performing 1215 may, but notnecessarily, include, for example, antenna 1025, transceiver 1015,communications manager 1020, memory 1030 (including code 1035),processor 1040 and/or bus 1045.

At 1220, the method may include receiving, from the second UE, a messageincluding packet-level information that indicates a sufficiency of thefirst amount of redundancy for encoding using the rateless encodingalgorithm, wherein the packet-level information that indicates thesufficiency of the first amount of redundancy indicates an estimatedloss probability for the first packet. The operations of 1220 may beperformed in accordance with examples as disclosed herein. In someexamples, aspects of the operations of 1220 may be performed by asidelink feedback receiver 940 as described with reference to FIG. 9 .Additionally or alternatively, means for performing 1220 may, but notnecessarily, include, for example, antenna 1025, transceiver 1015,communications manager 1020, memory 1030 (including code 1035),processor 1040 and/or bus 1045.

At 1225, the method may include determining a second amount ofredundancy based on the estimated loss probability. The operations of1225 may be performed in accordance with examples as disclosed herein.In some examples, aspects of the operations of 1225 may be performed bya redundancy manager 960 as described with reference to FIG. 9 .Additionally or alternatively, means for performing 1225 may, but notnecessarily, include, for example, antenna 1025, transceiver 1015,communications manager 1020, memory 1030 (including code 1035),processor 1040 and/or bus 1045.

At 1230, the method may include encoding a second packet using therateless encoding algorithm and in accordance with the second amount ofredundancy to obtain an encoded second packet, the second amount ofredundancy different than the first amount of redundancy and based onthe sufficiency of the first amount of redundancy for encoding using therateless encoding algorithm. The operations of 1230 may be performed inaccordance with examples as disclosed herein. In some examples, aspectsof the operations of 1230 may be performed by a packet encoder 930 asdescribed with reference to FIG. 9 . Additionally or alternatively,means for performing 1230 may, but not necessarily, include, forexample, antenna 1025, transceiver 1015, communications manager 1020,memory 1030 (including code 1035), processor 1040 and/or bus 1045.

At 1235, the method may include transmitting the encoded second packetto the second UE via the sidelink channel. The operations of 1235 may beperformed in accordance with examples as disclosed herein. In someexamples, aspects of the operations of 1235 may be performed by asidelink message transmitter 935 as described with reference to FIG. 9 .Additionally or alternatively, means for performing 1235 may, but notnecessarily, include, for example, antenna 1025, transceiver 1015,communications manager 1020, memory 1030 (including code 1035),processor 1040 and/or bus 1045.

FIG. 13 shows a flowchart illustrating a method 1300 that supportsadaptive rateless coding for sidelink communications in accordance withaspects of the present disclosure. The operations of the method 1300 maybe implemented by a UE or its components as described herein. Forexample, the operations of the method 1300 may be performed by a UE 115as described with reference to FIGS. 1 through 10 . In some examples, aUE may execute a set of instructions to control the functional elementsof the UE to perform the described functions. Additionally oralternatively, the UE may perform aspects of the described functionsusing special-purpose hardware.

At 1305, the method may include receiving, from a base station,signaling that indicates a first amount of redundancy for encoding usinga rateless encoding algorithm. The operations of 1305 may be performedin accordance with examples as disclosed herein. In some examples,aspects of the operations of 1305 may be performed by a direct linkmanager 925 as described with reference to FIG. 9 . Additionally oralternatively, means for performing 1305 may, but not necessarily,include, for example, antenna 1025, transceiver 1015, communicationsmanager 1020, memory 1030 (including code 1035), processor 1040 and/orbus 1045.

At 1310, the method may include encoding a first packet using therateless encoding algorithm and in accordance with the first amount ofredundancy to obtain an encoded first packet. The operations of 1310 maybe performed in accordance with examples as disclosed herein. In someexamples, aspects of the operations of 1310 may be performed by a packetencoder 930 as described with reference to FIG. 9 . Additionally oralternatively, means for performing 1310 may, but not necessarily,include, for example, antenna 1025, transceiver 1015, communicationsmanager 1020, memory 1030 (including code 1035), processor 1040 and/orbus 1045.

At 1315, the method may include transmitting the encoded first packet toa second UE via a sidelink channel. The operations of 1315 may beperformed in accordance with examples as disclosed herein. In someexamples, aspects of the operations of 1315 may be performed by asidelink message transmitter 935 as described with reference to FIG. 9 .Additionally or alternatively, means for performing 1315 may, but notnecessarily, include, for example, antenna 1025, transceiver 1015,communications manager 1020, memory 1030 (including code 1035),processor 1040 and/or bus 1045.

At 1320, the method may include receiving, from the second UE, a messageincluding packet-level information that indicates a second amount ofredundancy for encoding using the rateless encoding algorithm, thesecond amount of redundancy different than the first amount ofredundancy and based at least in part on a sufficiency of the firstamount of redundancy for encoding using the rateless encoding algorithm.The operations of 1320 may be performed in accordance with examples asdisclosed herein. In some examples, aspects of the operations of 1320may be performed by a sidelink feedback receiver 940 as described withreference to FIG. 9 . Additionally or alternatively, means forperforming 1320 may, but not necessarily, include, for example, antenna1025, transceiver 1015, communications manager 1020, memory 1030(including code 1035), processor 1040 and/or bus 1045.

At 1325, the method may include encoding a second packet using therateless encoding algorithm and in accordance with the second amount ofredundancy to obtain an encoded second packet. The operations of 1325may be performed in accordance with examples as disclosed herein. Insome examples, aspects of the operations of 1325 may be performed by apacket encoder 930 as described with reference to FIG. 9 . Additionallyor alternatively, means for performing 1330 may, but not necessarily,include, for example, antenna 1025, transceiver 1015, communicationsmanager 1020, memory 1030 (including code 1035), processor 1040 and/orbus 1045.

At 1330, the method may include transmitting the encoded second packetto the second UE via the sidelink channel. The operations of 1330 may beperformed in accordance with examples as disclosed herein. In someexamples, aspects of the operations of 1330 may be performed by asidelink message transmitter 935 as described with reference to FIG. 9 .Additionally or alternatively, means for performing 1335 may, but notnecessarily, include, for example, antenna 1025, transceiver 1015,communications manager 1020, memory 1030 (including code 1035),processor 1040 and/or bus 1045.

FIG. 14 shows a flowchart illustrating a method 1400 that supportsadaptive rateless coding for sidelink communications in accordance withaspects of the present disclosure. The operations of the method 1400 maybe implemented by a UE or its components as described herein. Forexample, the operations of the method 1400 may be performed by a UE 115as described with reference to FIGS. 1 through 10 . In some examples, aUE may execute a set of instructions to control the functional elementsof the UE to perform the described functions. Additionally oralternatively, the UE may perform aspects of the described functionsusing special-purpose hardware.

At 1405, the method may include receiving, from a base station,signaling that indicates a first amount of redundancy for encoding usinga rateless encoding algorithm. The operations of 1405 may be performedin accordance with examples as disclosed herein. In some examples,aspects of the operations of 1405 may be performed by a direct linkmanager 925 as described with reference to FIG. 9 . Additionally oralternatively, means for performing 1405 may, but not necessarily,include, for example, antenna 1025, transceiver 1015, communicationsmanager 1020, memory 1030 (including code 1035), processor 1040 and/orbus 1045.

At 1410, the method may include encoding a first packet using therateless encoding algorithm and in accordance with the first amount ofredundancy to obtain an encoded first packet. The operations of 1410 maybe performed in accordance with examples as disclosed herein. In someexamples, aspects of the operations of 1410 may be performed by a packetencoder 930 as described with reference to FIG. 9 . Additionally oralternatively, means for performing 1410 may, but not necessarily,include, for example, antenna 1025, transceiver 1015, communicationsmanager 1020, memory 1030 (including code 1035), processor 1040 and/orbus 1045.

At 1415, the method may include transmitting the encoded first packet toa second UE via a sidelink channel. The operations of 1415 may beperformed in accordance with examples as disclosed herein. In someexamples, aspects of the operations of 1415 may be performed by asidelink message transmitter 935 as described with reference to FIG. 9 .Additionally or alternatively, means for performing 1415 may, but notnecessarily, include, for example, antenna 1025, transceiver 1015,communications manager 1020, memory 1030 (including code 1035),processor 1040 and/or bus 1045.

At 1420, the method may include receiving, from the second UE, a messageincluding an indication of whether the first packet was successfullydecoded. The operations of 1420 may be performed in accordance withexamples as disclosed herein. In some examples, aspects of theoperations of 1420 may be performed by a sidelink feedback receiver 940as described with reference to FIG. 9 . Additionally or alternatively,means for performing 1420 may, but not necessarily, include, forexample, antenna 1025, transceiver 1015, communications manager 1020,memory 1030 (including code 1035), processor 1040 and/or bus 1045.

At 1425, the method may include encoding a second packet using therateless encoding algorithm and in accordance with a second amount ofredundancy to obtain an encoded second packet, the second amount ofredundancy different than the first amount of redundancy and based onthe indication of whether the first packet was successfully decoded. Theoperations of 1425 may be performed in accordance with examples asdisclosed herein. In some examples, aspects of the operations of 1425may be performed by a packet encoder 930 as described with reference toFIG. 9 . Additionally or alternatively, means for performing 1430 may,but not necessarily, include, for example, antenna 1025, transceiver1015, communications manager 1020, memory 1030 (including code 1035),processor 1040 and/or bus 1045.

At 1435, the method may include transmitting the encoded second packetto the second UE via the sidelink channel. The operations of 1435 may beperformed in accordance with examples as disclosed herein. In someexamples, aspects of the operations of 1435 may be performed by asidelink message transmitter 935 as described with reference to FIG. 9 .Additionally or alternatively, means for performing 1435 may, but notnecessarily, include, for example, antenna 1025, transceiver 1015,communications manager 1020, memory 1030 (including code 1035),processor 1040 and/or bus 1045.

FIG. 15 shows a flowchart illustrating a method 1500 that supportsadaptive rateless coding for sidelink communications in accordance withaspects of the present disclosure. The operations of the method 1500 maybe implemented by a UE or its components as described herein. Forexample, the operations of the method 1500 may be performed by a UE 115as described with reference to FIGS. 1 through 10 . In some examples, aUE may execute a set of instructions to control the functional elementsof the UE to perform the described functions. Additionally oralternatively, the UE may perform aspects of the described functionsusing special-purpose hardware.

At 1505, the method may include receiving, from a base station,signaling that indicates a first amount of redundancy for encoding usinga rateless encoding algorithm. The operations of 1505 may be performedin accordance with examples as disclosed herein. In some examples,aspects of the operations of 1505 may be performed by a direct linkmanager 925 as described with reference to FIG. 9 . Additionally oralternatively, means for performing 1505 may, but not necessarily,include, for example, antenna 1025, transceiver 1015, communicationsmanager 1020, memory 1030 (including code 1035), processor 1040 and/orbus 1045.

At 1510, the method may include receiving, from a first UE via asidelink channel, a packet encoded using the rateless encoding algorithmand in accordance with the first amount of redundancy. The operations of1510 may be performed in accordance with examples as disclosed herein.In some examples, aspects of the operations of 1510 may be performed bya sidelink message receiver 945 as described with reference to FIG. 9 .Additionally or alternatively, means for performing 1510 may, but notnecessarily, include, for example, antenna 1025, transceiver 1015,communications manager 1020, memory 1030 (including code 1035),processor 1040 and/or bus 1045.

At 1515, the method may include decoding the packet using a ratelessdecoding algorithm that corresponds to the rateless encoding algorithm.The operations of 1515 may be performed in accordance with examples asdisclosed herein. In some examples, aspects of the operations of 1515may be performed by a packet decoder 950 as described with reference toFIG. 9 . Additionally or alternatively, means for performing 1515 may,but not necessarily, include, for example, antenna 1025, transceiver1015, communications manager 1020, memory 1030 (including code 1035),processor 1040 and/or bus 1045.

At 1520, the method may include transmitting, to the first UE based ondecoding the packet using the rateless decoding algorithm, a messageincluding packet-level information that indicates a sufficiency of thefirst amount of redundancy for encoding using the rateless encodingalgorithm. The message may indicate that the first amount of redundancyis sufficient for encoding using the rateless encoding algorithm, or,alternatively, the message may indicate that the first amount ofredundancy is insufficient for encoding using the rateless encodingalgorithm, as discussed above. The operations of 1520 may be performedin accordance with examples as disclosed herein. In some examples,aspects of the operations of 1520 may be performed by a sidelinkfeedback transmitter 955 as described with reference to FIG. 9 .Additionally or alternatively, means for performing 1520 may, but notnecessarily, include, for example, antenna 1025, transceiver 1015,communications manager 1020, memory 1030 (including code 1035),processor 1040 and/or bus 1045.

FIG. 16 shows a flowchart illustrating a method 1600 that supportsadaptive rateless coding for sidelink communications in accordance withaspects of the present disclosure. The operations of the method 1600 maybe implemented by a UE or its components as described herein. Forexample, the operations of the method 1600 may be performed by a UE 115as described with reference to FIGS. 1 through 10 . In some examples, aUE may execute a set of instructions to control the functional elementsof the UE to perform the described functions. Additionally oralternatively, the UE may perform aspects of the described functionsusing special-purpose hardware.

At 1605, the method may include receiving, from a base station,signaling that indicates a first amount of redundancy for encoding usinga rateless encoding algorithm. The operations of 1605 may be performedin accordance with examples as disclosed herein. In some examples,aspects of the operations of 1605 may be performed by a direct linkmanager 925 as described with reference to FIG. 9 . Additionally oralternatively, means for performing 1605 may, but not necessarily,include, for example, antenna 1025, transceiver 1015, communicationsmanager 1020, memory 1030 (including code 1035), processor 1040 and/orbus 1045.

At 1610, the method may include receiving, from a first UE via asidelink channel, a packet encoded using the rateless encoding algorithmand in accordance with the first amount of redundancy. The operations of1610 may be performed in accordance with examples as disclosed herein.In some examples, aspects of the operations of 1610 may be performed bya sidelink message receiver 945 as described with reference to FIG. 9 .Additionally or alternatively, means for performing 1610 may, but notnecessarily, include, for example, antenna 1025, transceiver 1015,communications manager 1020, memory 1030 (including code 1035),processor 1040 and/or bus 1045.

At 1615, the method may include decoding the packet using a ratelessdecoding algorithm that corresponds to the rateless encoding algorithm.The operations of 1615 may be performed in accordance with examples asdisclosed herein. In some examples, aspects of the operations of 1615may be performed by a packet decoder 950 as described with reference toFIG. 9 . Additionally or alternatively, means for performing 1615 may,but not necessarily, include, for example, antenna 1025, transceiver1015, communications manager 1020, memory 1030 (including code 1035),processor 1040 and/or bus 1045.

At 1620, the method may include estimating a loss probability for thepacket. The operations of 1620 may be performed in accordance withexamples as disclosed herein. In some examples, aspects of theoperations of 1620 may be performed by a loss probability estimator 965as described with reference to FIG. 9 . Additionally or alternatively,means for performing 1620 may, but not necessarily, include, forexample, antenna 1025, transceiver 1015, communications manager 1020,memory 1030 (including code 1035), processor 1040 and/or bus 1045.

At 1625, the method may include transmitting, to the first UE based ondecoding the packet using the rateless decoding algorithm, a messageincluding packet-level information that indicates a sufficiency of thefirst amount of redundancy for encoding using the rateless encodingalgorithm, where the packet-level information that indicates thesufficiency of the first amount of redundancy for encoding using therateless encoding algorithm indicates the estimated loss probability forthe packet. The operations of 1625 may be performed in accordance withexamples as disclosed herein. In some examples, aspects of theoperations of 1625 may be performed by a sidelink feedback transmitter955 as described with reference to FIG. 9 . Additionally oralternatively, means for performing 1625 may, but not necessarily,include, for example, antenna 1025, transceiver 1015, communicationsmanager 1020, memory 1030 (including code 1035), processor 1040 and/orbus 1045.

FIG. 17 shows a flowchart illustrating a method 1700 that supportsadaptive rateless coding for sidelink communications in accordance withaspects of the present disclosure. The operations of the method 1700 maybe implemented by a UE or its components as described herein. Forexample, the operations of the method 1700 may be performed by a UE 115as described with reference to FIGS. 1 through 10 . In some examples, aUE may execute a set of instructions to control the functional elementsof the UE to perform the described functions. Additionally oralternatively, the UE may perform aspects of the described functionsusing special-purpose hardware.

At 1705, the method may include receiving, from a base station,signaling that indicates a first amount of redundancy for encoding usinga rateless encoding algorithm. The operations of 1705 may be performedin accordance with examples as disclosed herein. In some examples,aspects of the operations of 1705 may be performed by a direct linkmanager 925 as described with reference to FIG. 9 . Additionally oralternatively, means for performing 1705 may, but not necessarily,include, for example, antenna 1025, transceiver 1015, communicationsmanager 1020, memory 1030 (including code 1035), processor 1040 and/orbus 1045.

At 1710, the method may include receiving, from a first UE via asidelink channel, a packet encoded using the rateless encoding algorithmand in accordance with the first amount of redundancy. The operations of1710 may be performed in accordance with examples as disclosed herein.In some examples, aspects of the operations of 1710 may be performed bya sidelink message receiver 945 as described with reference to FIG. 9 .Additionally or alternatively, means for performing 1710 may, but notnecessarily, include, for example, antenna 1025, transceiver 1015,communications manager 1020, memory 1030 (including code 1035),processor 1040 and/or bus 1045.

At 1715, the method may include decoding the packet using a ratelessdecoding algorithm that corresponds to the rateless encoding algorithm.The operations of 1715 may be performed in accordance with examples asdisclosed herein. In some examples, aspects of the operations of 1715may be performed by a packet decoder 950 as described with reference toFIG. 9 . Additionally or alternatively, means for performing 1715 may,but not necessarily, include, for example, antenna 1025, transceiver1015, communications manager 1020, memory 1030 (including code 1035),processor 1040 and/or bus 1045.

At 1720, the method may include estimating a loss probability for thepacket. The operations of 1720 may be performed in accordance withexamples as disclosed herein. In some examples, aspects of theoperations of 1720 may be performed by a loss probability estimator 965as described with reference to FIG. 9 . Additionally or alternatively,means for performing 1720 may, but not necessarily, include, forexample, antenna 1025, transceiver 1015, communications manager 1020,memory 1030 (including code 1035), processor 1040 and/or bus 1045.

At 1725, the method may include determining a second amount ofredundancy based on the estimated loss probability for the packet. Theoperations of 1725 may be performed in accordance with examples asdisclosed herein. In some examples, aspects of the operations of 1725may be performed by a redundancy manager 960 as described with referenceto FIG. 9 . Additionally or alternatively, means for performing 1725may, but not necessarily, include, for example, antenna 1025,transceiver 1015, communications manager 1020, memory 1030 (includingcode 1035), processor 1040 and/or bus 1045.

At 1730, the method may include transmitting, to the first UE based ondecoding the packet using the rateless decoding algorithm, a messageincluding packet-level information that indicates a sufficiency of thefirst amount of redundancy for encoding using the rateless encodingalgorithm, where the packet-level information that indicates thesufficiency of the first amount of redundancy for encoding using therateless encoding algorithm indicates the second amount of redundancy.The operations of 1730 may be performed in accordance with examples asdisclosed herein. In some examples, aspects of the operations of 1730may be performed by a sidelink feedback transmitter 955 as describedwith reference to FIG. 9 . Additionally or alternatively, means forperforming 1730 may, but not necessarily, include, for example, antenna1025, transceiver 1015, communications manager 1020, memory 1030(including code 1035), processor 1040 and/or bus 1045.

FIG. 18 shows a flowchart illustrating a method 1800 that supportsadaptive rateless coding for sidelink communications in accordance withaspects of the present disclosure. The operations of the method 1800 maybe implemented by a UE or its components as described herein. Forexample, the operations of the method 1800 may be performed by a UE 115as described with reference to FIGS. 1 through 10 . In some examples, aUE may execute a set of instructions to control the functional elementsof the UE to perform the described functions. Additionally oralternatively, the UE may perform aspects of the described functionsusing special-purpose hardware.

At 1805, the method may include receiving, from a base station,signaling that indicates a first amount of redundancy for encoding usinga rateless encoding algorithm. The operations of 1805 may be performedin accordance with examples as disclosed herein. In some examples,aspects of the operations of 1805 may be performed by a direct linkmanager 925 as described with reference to FIG. 9 . Additionally oralternatively, means for performing 1805 may, but not necessarily,include, for example, antenna 1025, transceiver 1015, communicationsmanager 1020, memory 1030 (including code 1035), processor 1040 and/orbus 1045.

At 1810, the method may include receiving, from a first UE via asidelink channel, a packet encoded using the rateless encoding algorithmand in accordance with the first amount of redundancy. The operations of1810 may be performed in accordance with examples as disclosed herein.In some examples, aspects of the operations of 1810 may be performed bya sidelink message receiver 945 as described with reference to FIG. 9 .Additionally or alternatively, means for performing 1810 may, but notnecessarily, include, for example, antenna 1025, transceiver 1015,communications manager 1020, memory 1030 (including code 1035),processor 1040 and/or bus 1045.

At 1815, the method may include decoding the packet using a ratelessdecoding algorithm that corresponds to the rateless encoding algorithm.The operations of 1815 may be performed in accordance with examples asdisclosed herein. In some examples, aspects of the operations of 1815may be performed by a packet decoder 950 as described with reference toFIG. 9 . Additionally or alternatively, means for performing 1815 may,but not necessarily, include, for example, antenna 1025, transceiver1015, communications manager 1020, memory 1030 (including code 1035),processor 1040 and/or bus 1045.

At 1820, the method may include transmitting, to the first UE based ondecoding the packet using the rateless decoding algorithm, a messageincluding packet-level information that indicates a sufficiency of thefirst amount of redundancy for encoding using the rateless encodingalgorithm, wherein the packet-level information that indicates thesufficiency of the first amount of redundancy for encoding using therateless encoding algorithm comprises an indication of whether thepacket was successfully decoded. The operations of 1820 may be performedin accordance with examples as disclosed herein. In some examples,aspects of the operations of 1820 may be performed by a sidelinkfeedback transmitter 955 as described with reference to FIG. 9 .Additionally or alternatively, means for performing 1820 may, but notnecessarily, include, for example, antenna 1025, transceiver 1015,communications manager 1020, memory 1030 (including code 1035),processor 1040 and/or bus 1045.

FIG. 19 shows a flowchart illustrating a method 1900 that supportsadaptive rateless coding for sidelink communications in accordance withaspects of the present disclosure. The operations of the method 1900 maybe implemented by a UE or its components as described herein. Forexample, the operations of the method 1900 may be performed by a UE 115as described with reference to FIGS. 1 through 10 . In some examples, aUE may execute a set of instructions to control the functional elementsof the UE to perform the described functions. Additionally oralternatively, the UE may perform aspects of the described functionsusing special-purpose hardware.

At 1905, the method may include receiving, from a base station,signaling that indicates a first amount of redundancy for encoding usinga rateless encoding algorithm. The operations of 1905 may be performedin accordance with examples as disclosed herein. In some examples,aspects of the operations of 1905 may be performed by a direct linkmanager 925 as described with reference to FIG. 9 . Additionally oralternatively, means for performing 1905 may, but not necessarily,include, for example, antenna 1025, transceiver 1015, communicationsmanager 1020, memory 1030 (including code 1035), processor 1040 and/orbus 1045.

At 1910, the method may include receiving, from a first UE via asidelink channel, a packet encoded using the rateless encoding algorithmand in accordance with the first amount of redundancy. The operations of1910 may be performed in accordance with examples as disclosed herein.In some examples, aspects of the operations of 1910 may be performed bya sidelink message receiver 945 as described with reference to FIG. 9 .Additionally or alternatively, means for performing 1910 may, but notnecessarily, include, for example, antenna 1025, transceiver 1015,communications manager 1020, memory 1030 (including code 1035),processor 1040 and/or bus 1045.

At 1915, the method may include decoding the packet using a ratelessdecoding algorithm that corresponds to the rateless encoding algorithm.The operations of 1915 may be performed in accordance with examples asdisclosed herein. In some examples, aspects of the operations of 1915may be performed by a packet decoder 950 as described with reference toFIG. 9 . Additionally or alternatively, means for performing 1915 may,but not necessarily, include, for example, antenna 1025, transceiver1015, communications manager 1020, memory 1030 (including code 1035),processor 1040 and/or bus 1045.

At 1920, the method may include transmitting, to the first UE based ondecoding the packet using the rateless decoding algorithm, a messageincluding packet-level information that indicates a sufficiency of thefirst amount of redundancy for encoding using the rateless encodingalgorithm. The message may indicate that the first amount of redundancyis sufficient for encoding using the rateless encoding algorithm, or,alternatively, the message may indicate that the first amount ofredundancy is insufficient for encoding using the rateless encodingalgorithm, as discussed above. The operations of 1920 may be performedin accordance with examples as disclosed herein. In some examples,aspects of the operations of 1920 may be performed by a sidelinkfeedback transmitter 955 as described with reference to FIG. 9 .Additionally or alternatively, means for performing 1920 may, but notnecessarily, include, for example, antenna 1025, transceiver 1015,communications manager 1020, memory 1030 (including code 1035),processor 1040 and/or bus 1045.

At 1925, the method may include receiving, from the first UE via thesidelink channel, a second packet encoded using the rateless encodingalgorithm and in accordance with a second amount of redundancy differentthan the first amount of redundancy, the second amount of redundancydifferent than the first amount of redundancy and based on thesufficiency of the first amount of redundancy for encoding using therateless encoding algorithm. The operations of 1925 may be performed inaccordance with examples as disclosed herein. In some examples, aspectsof the operations of 1925 may be performed by a sidelink messagereceiver 945 as described with reference to FIG. 9 . Additionally oralternatively, means for performing 1925 may, but not necessarily,include, for example, antenna 1025, transceiver 1015, communicationsmanager 1020, memory 1030 (including code 1035), processor 1040 and/orbus 1045.

The following provides an overview of aspects of the present disclosure:

Aspect 1: A method for wireless communications at a first UE,comprising: receiving, from a base station, signaling that indicates afirst amount of redundancy for encoding using a rateless encodingalgorithm; encoding a first packet using the rateless encoding algorithmand in accordance with the first amount of redundancy to obtain anencoded first packet; transmitting the encoded first packet to a secondUE via a sidelink channel; receiving, from the second UE, a messagecomprising information (e.g., packet-level information) that indicates asufficiency of the first amount of redundancy for encoding using therateless encoding algorithm; encoding a second packet using the ratelessencoding algorithm and in accordance with a second amount of redundancyto obtain an encoded second packet, the second amount of redundancydifferent than the first amount of redundancy and based at least in parton the sufficiency of the first amount of redundancy for encoding usingthe rateless encoding algorithm; and transmitting the encoded secondpacket to the second UE via the sidelink channel.

Aspect 2: The method of aspect 1, wherein the information that indicatesthe sufficiency of the first amount of redundancy indicates an estimatedloss probability for the first packet, the method further comprising:determining the second amount of redundancy based at least in part onthe estimated loss probability.

Aspect 3: The method of aspect 2, wherein determining the second amountof redundancy based at least in part on the estimated loss probabilitycomprises: identifying the second amount of redundancy based at least inpart on an index value for a lookup table, wherein the index value forthe lookup table corresponds to the estimated loss probability.

Aspect 4: The method of any of aspects 1 through 3, wherein receivingthe message comprising the information that indicates the sufficiency ofthe first amount of redundancy comprises: receiving, in the message, anindication of the second amount of redundancy.

Aspect 5: The method of any of aspects 1 through 4, wherein receivingthe message comprising the information that indicates the sufficiency ofthe first amount of redundancy comprises: receiving, in the message, arequest to decrease a redundancy amount for encoding using the ratelessencoding algorithm, wherein the second amount of redundancy is less thanthe first amount of redundancy.

Aspect 6: The method of any of aspects 1 through 5, wherein receivingthe message comprising the information that indicates the sufficiency ofthe first amount of redundancy comprises: receiving, in the message, arequest to increase a redundancy amount for encoding using the ratelessencoding algorithm, wherein the second amount of redundancy is greaterthan the first amount of redundancy.

Aspect 7: The method of any of aspects 1 through 6, wherein receivingthe message comprising the information that indicates the sufficiency ofthe first amount of redundancy comprises: receiving, in the message, anindication of whether the first packet was successfully decoded, whereinthe second amount of redundancy is based at least in part on theindication.

Aspect 8: The method of any of aspects 1 through 7, wherein encoding thefirst packet using the rateless encoding algorithm comprises: dividingthe first packet into a set of subpackets comprising a first quantity ofsubpackets; and generating a set of encoded subpackets based at least inpart on the set of subpackets and using the rateless encoding algorithm,wherein the set of encoded subpackets comprises a second quantity ofencoded subpackets that is greater than the first quantity ofsubpackets, and wherein an amount of redundancy for encoding using therateless encoding algorithm comprises a difference between the secondquantity of encoded subpackets and the first quantity of subpackets.

Aspect 9: The method of any of aspects 1 through 8, further comprising:receiving, from the second UE, a second message comprising information(e.g., packet-level information) that indicates a second sufficiency ofthe second amount of redundancy for encoding using the rateless encodingalgorithm; transmitting, to the base station and based at least in parton the information that indicates the second sufficiency of the secondamount of redundancy for encoding using the rateless encoding algorithm,a request to switch from using the rateless encoding algorithm to usinga different rateless encoding algorithm for sidelink communications;receiving, from the base station, an indication of a second ratelessencoding algorithm that comprises the different rateless encodingalgorithm; encoding a third packet using the second rateless encodingalgorithm to obtain an encoded third packet; and transmitting theencoded third packet to the second UE via the sidelink channel.

Aspect 10: The method of any of aspects 1 through 9, further comprising:receiving an indication of a quantity of subpackets into which to divideeach packet for encoding using the rateless encoding algorithm, anindication of the rateless encoding algorithm, an indication of arateless decoding algorithm, an indication of a pool of transmissionresources for sidelink communications by the first UE, or anycombination thereof.

Aspect 11: A method for wireless communications at a second UE,comprising: receiving, from a base station, signaling that indicates afirst amount of redundancy for encoding using a rateless encodingalgorithm; receiving, from a first UE via a sidelink channel, a packetencoded using the rateless encoding algorithm and in accordance with thefirst amount of redundancy; decoding the packet using a ratelessdecoding algorithm that corresponds to the rateless encoding algorithm;and transmitting, to the first UE based at least in part on decoding thepacket using the rateless decoding algorithm, a message comprisinginformation (e.g., packet-level information) that indicates asufficiency of the first amount of redundancy for encoding using therateless encoding algorithm.

Aspect 12: The method of aspect 11, further comprising: estimating aloss probability for the packet, wherein the information that indicatesthe sufficiency of the first amount of redundancy for encoding using therateless encoding algorithm indicates the estimated loss probability forthe packet.

Aspect 13: The method of aspect 12, wherein estimating the lossprobability for the packet comprises: determining a first quantity ofsubpackets received by the second UE during a time period and a secondquantity of subpackets transmitted by the first UE during the timeperiod, the loss probability based at least in part on a ratio betweenthe first quantity of subpackets received by the second UE and thesecond quantity of subpackets transmitted by the first UE during thetime period.

Aspect 14: The method of any of aspects 11 through 13, furthercomprising: estimating a loss probability for the packet; anddetermining a second amount of redundancy based at least in part on theestimated loss probability for the packet, wherein the information thatindicates the sufficiency of the first amount of redundancy for encodingusing the rateless encoding algorithm indicates the second amount ofredundancy.

Aspect 15: The method of aspect 14, wherein determining the secondamount of redundancy based at least in part on the estimated lossprobability comprises: identifying the second amount of redundancy basedat least in part on an index value for a lookup table, wherein the indexvalue for the lookup table corresponds to the estimated lossprobability.

Aspect 16: The method of any of aspects 11 through 15, whereintransmitting the message comprising the information that indicates thesufficiency of the first amount of redundancy comprises: transmitting,in the message, a request to increase a redundancy amount.

Aspect 17: The method of any of aspects 11 through 16, whereintransmitting the message comprising the information that indicates thesufficiency of the first amount of redundancy comprises: transmitting,in the message, a request to decrease a redundancy amount.

Aspect 18: The method of any of aspects 11 through 17, whereintransmitting the message comprising the information that indicates thesufficiency of the first amount of redundancy comprises: transmitting,in the message, an indication of whether the packet was successfullydecoded.

Aspect 19: The method of any of aspects 11 through 18, wherein decodingthe packet using the rateless decoding algorithm comprises: identifyinga set of encoded subpackets received for the packet, the set of encodedsubpackets comprising a first quantity of encoded subpackets greaterthan or equal to a second quantity of original subpackets encoded usingthe rateless encoding algorithm; decoding the set of encoded subpacketsto obtain a set of decoded subpackets comprising a third quantity ofdecoded subpackets, the third quantity greater than or equal to thesecond quantity; and attempting to obtain the packet based at least inpart on the set of decoded subpackets.

Aspect 20: The method of aspect 19, wherein a probability of success fordecoding the packet using the rateless decoding algorithm is based atleast in part on a difference between the first quantity of encodedsubpackets and the second quantity of original subpackets.

Aspect 21: The method of any of aspects 11 through 20, furthercomprising: transmitting, to the base station, a request to transmit theinformation that indicates the sufficiency of the first amount ofredundancy for encoding using the rateless encoding algorithm; andreceiving, from the base station, a grant in response to the request,wherein the message comprising the information that indicates thesufficiency of the first amount of redundancy for encoding using therateless encoding algorithm is transmitted based at least in part on thegrant from the base station.

Aspect 22: The method of aspect 21, wherein transmitting the request totransmit the information that indicates the sufficiency of the firstamount of redundancy for encoding using the rateless encoding algorithmis based at least in part on one of a condition of the sidelink channelor a quality of service target associated with the sidelink channel.

Aspect 23: The method of any of aspects 11 through 22, furthercomprising: receiving, from the base station, a request to transmit theinformation that indicates the sufficiency of the first amount ofredundancy for encoding using the rateless encoding algorithm, whereintransmitting the message comprising the information that indicates thesufficiency of the first amount of redundancy for encoding using therateless encoding algorithm is transmitted based at least in part on therequest from the base station.

Aspect 24: The method of any of aspects 11 through 23, furthercomprising: receiving, from the first UE via the sidelink channel, asecond packet encoded using the rateless encoding algorithm and inaccordance with a second amount of redundancy different than the firstamount of redundancy, the second amount of redundancy different than thefirst amount of redundancy and based at least in part on the sufficiencyof the first amount of redundancy for encoding using the ratelessencoding algorithm.

Aspect 25: The method of any of aspects 11 through 24, furthercomprising: receiving an indication of a quantity of original subpacketsfor the packet encoded using the rateless encoding algorithm, anindication of the rateless encoding algorithm, an indication of therateless decoding algorithm, an indication of a pool of transmissionresources for sidelink communications by the second UE, or anycombination thereof.

Aspect 26: An apparatus comprising a memory, a transceiver, and at leastone processor in communication with the memory and the transceiver, theat least one processor configured to cause the apparatus to perform amethod of any of aspects 1 through 10.

Aspect 27: An apparatus for wireless communications at a first UE,comprising at least one means for performing a method of any of aspects1 through 10.

Aspect 28: A non-transitory computer-readable medium storing code forwireless communications at a first UE, the code comprising instructionsexecutable by a processor to perform a method of any of aspects 1through 10.

Aspect 29: An apparatus comprising a memory, a transceiver, and at leastone processor in communication with the memory and the transceiver, theat least one processor configured to cause the apparatus to perform amethod of any of aspects 11 through 25.

Aspect 30: An apparatus for wireless communications at a second UE,comprising at least one means for performing a method of any of aspects11 through 25.

Aspect 31: A non-transitory computer-readable medium storing code forwireless communications at a second UE, the code comprising instructionsexecutable by a processor to perform a method of any of aspects 11through 25.

It should be noted that the methods described herein describe possibleimplementations, and that the operations and the steps may be rearrangedor otherwise modified and that other implementations are possible.Further, aspects from two or more of the methods may be combined.

Although aspects of an LTE, LTE-A, LTE-A Pro, or NR system may bedescribed for purposes of example, and LTE, LTE-A, LTE-A Pro, or NRterminology may be used in much of the description, the techniquesdescribed herein are applicable beyond LTE, LTE-A, LTE-A Pro, or NRnetworks. For example, the described techniques may be applicable tovarious other wireless communications systems such as Ultra MobileBroadband (UMB), Institute of Electrical and Electronics Engineers(IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM, aswell as other systems and radio technologies not explicitly mentionedherein.

Information and signals described herein may be represented using any ofa variety of different technologies and techniques. For example, data,instructions, commands, information, signals, bits, symbols, and chipsthat may be referenced throughout the description may be represented byvoltages, currents, electromagnetic waves, magnetic fields or particles,optical fields or particles, or any combination thereof.

The various illustrative blocks and components described in connectionwith the disclosure herein may be implemented or performed with ageneral-purpose processor, a DSP, an ASIC, a CPU, an FPGA or otherprogrammable logic device, discrete gate or transistor logic, discretehardware components, or any combination thereof designed to perform thefunctions described herein. A general-purpose processor may be amicroprocessor, but in the alternative, the processor may be anyprocessor, controller, microcontroller, or state machine. A processormay also be implemented as a combination of computing devices (e.g., acombination of a DSP and a microprocessor, multiple microprocessors, oneor more microprocessors in conjunction with a DSP core, or any othersuch configuration).

The functions described herein may be implemented in hardware, softwareexecuted by a processor, firmware, or any combination thereof. Ifimplemented in software executed by a processor, the functions may bestored on or transmitted over as one or more instructions or code on acomputer-readable medium. Other examples and implementations are withinthe scope of the disclosure and appended claims. For example, due to thenature of software, functions described herein may be implemented usingsoftware executed by a processor, hardware, firmware, hardwiring, orcombinations of any of these. Features implementing functions may alsobe physically located at various positions, including being distributedsuch that portions of functions are implemented at different physicallocations.

Computer-readable media includes both non-transitory computer storagemedia and communication media including any medium that facilitatestransfer of a computer program from one place to another. Anon-transitory storage medium may be any available medium that may beaccessed by a general-purpose or special-purpose computer. By way ofexample, and not limitation, non-transitory computer-readable media mayinclude RAM, ROM, electrically erasable programmable ROM (EEPROM), flashmemory, compact disk (CD) ROM or other optical disk storage, magneticdisk storage or other magnetic storage devices, or any othernon-transitory medium that may be used to carry or store desired programcode means in the form of instructions or data structures and that maybe accessed by a general-purpose or special-purpose computer, or ageneral-purpose or special-purpose processor. Also, any connection isproperly termed a computer-readable medium. For example, if the softwareis transmitted from a website, server, or other remote source using acoaxial cable, fiber optic cable, twisted pair, digital subscriber line(DSL), or wireless technologies such as infrared, radio, and microwave,then the coaxial cable, fiber optic cable, twisted pair, DSL, orwireless technologies such as infrared, radio, and microwave areincluded in the definition of computer-readable medium. Disk and disc,as used herein, include CD, laser disc, optical disc, digital versatiledisc (DVD), floppy disk and Blu-ray disc where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.Combinations of the above are also included within the scope ofcomputer-readable media.

As used herein, including in the claims, “or” as used in a list of items(e.g., a list of items prefaced by a phrase such as “at least one of” or“one or more of”) indicates an inclusive list such that, for example, alist of at least one of A, B, or C means A or B or C or AB or AC or BCor ABC (i.e., A and B and C). Also, as used herein, the phrase “basedon” shall not be construed as a reference to a closed set of conditions.For example, an example step that is described as “based on condition A”may be based on both a condition A and a condition B without departingfrom the scope of the present disclosure. In other words, as usedherein, the phrase “based on” shall be construed in the same manner asthe phrase “based at least in part on.”

The term “determine” or “determining” encompasses a wide variety ofactions and, therefore, “determining” can include calculating,computing, processing, deriving, investigating, looking up (such as vialooking up in a table, a database or another data structure),ascertaining and the like. Also, “determining” can include receiving(such as receiving information), accessing (such as accessing data in amemory) and the like. Also, “determining” can include resolving,selecting, choosing, establishing and other such similar actions.

In the appended figures, similar components or features may have thesame reference label. Further, various components of the same type maybe distinguished by following the reference label by a dash and a secondlabel that distinguishes among the similar components. If just the firstreference label is used in the specification, the description isapplicable to any one of the similar components having the same firstreference label irrespective of the second reference label, or othersubsequent reference label.

The description set forth herein, in connection with the appendeddrawings, describes example configurations and does not represent allthe examples that may be implemented or that are within the scope of theclaims. The term “example” used herein means “serving as an example,instance, or illustration,” and not “preferred” or “advantageous overother examples.” The detailed description includes specific details forthe purpose of providing an understanding of the described techniques.These techniques, however, may be practiced without these specificdetails. In some instances, known structures and devices are shown inblock diagram form in order to avoid obscuring the concepts of thedescribed examples.

The description herein is provided to enable a person having ordinaryskill in the art to make or use the disclosure. Various modifications tothe disclosure will be apparent to a person having ordinary skill in theart, and the generic principles defined herein may be applied to othervariations without departing from the scope of the disclosure. Thus, thedisclosure is not limited to the examples and designs described hereinbut is to be accorded the broadest scope consistent with the principlesand novel features disclosed herein.

What is claimed is:
 1. A method for wireless communications at a firstuser equipment (UE), comprising: receiving, from a base station,signaling that indicates a first amount of redundancy for encoding usinga rateless encoding algorithm; encoding a first packet using therateless encoding algorithm and in accordance with the first amount ofredundancy to obtain an encoded first packet; transmitting the encodedfirst packet to a second UE via a sidelink channel; receiving, from thesecond UE, a message comprising packet-level information that indicatesa sufficiency of the first amount of redundancy for encoding using therateless encoding algorithm; encoding a second packet using the ratelessencoding algorithm and in accordance with a second amount of redundancyto obtain an encoded second packet, the second amount of redundancydifferent than the first amount of redundancy and based at least in parton the sufficiency of the first amount of redundancy for encoding usingthe rateless encoding algorithm; and transmitting the encoded secondpacket to the second UE via the sidelink channel.
 2. The method of claim1, wherein receiving the message comprising the packet-level informationthat indicates the sufficiency of the first amount of redundancycomprises: receiving, in the message, an indication of the second amountof redundancy; receiving, in the message, a request to decrease aredundancy amount for encoding using the rateless encoding algorithm,wherein the second amount of redundancy is less than the first amount ofredundancy; receiving, in the message, a request to increase aredundancy amount for encoding using the rateless encoding algorithm,wherein the second amount of redundancy is greater than the first amountof redundancy; or receiving, in the message, an indication of whetherthe first packet was successfully decoded, wherein the second amount ofredundancy is based at least in part on the indication; or anycombination thereof.
 3. The method of claim 1, wherein receiving themessage comprising the packet-level information that indicates thesufficiency of the first amount of redundancy comprises receiving, inthe message, an indication of an estimated loss probability for thefirst packet, the method further comprising: determining the secondamount of redundancy based at least in part on the estimated lossprobability.
 4. The method of claim 3, wherein determining the secondamount of redundancy based at least in part on the estimated lossprobability comprises: identifying the second amount of redundancy basedat least in part on an index value for a lookup table, wherein the indexvalue for the lookup table corresponds to the estimated lossprobability.
 5. The method of claim 1, wherein encoding the first packetusing the rateless encoding algorithm comprises: dividing the firstpacket into a set of subpackets comprising a first quantity ofsubpackets; and generating a set of encoded subpackets based at least inpart on the set of subpackets and using the rateless encoding algorithm,wherein the set of encoded subpackets comprises a second quantity ofencoded subpackets that is greater than the first quantity ofsubpackets, and wherein an amount of redundancy for encoding using therateless encoding algorithm comprises a difference between the secondquantity of encoded subpackets and the first quantity of subpackets. 6.The method of claim 1, further comprising: receiving, from the secondUE, a second message comprising packet-level information that indicatesa second sufficiency of the second amount of redundancy for encodingusing the rateless encoding algorithm; transmitting, to the base stationand based at least in part on the packet-level information thatindicates the second sufficiency of the second amount of redundancy forencoding using the rateless encoding algorithm, a request to switch fromusing the rateless encoding algorithm to using a different ratelessencoding algorithm for sidelink communications; receiving, from the basestation, an indication of a second rateless encoding algorithm thatcomprises the different rateless encoding algorithm; encoding a thirdpacket using the second rateless encoding algorithm to obtain an encodedthird packet; and transmitting the encoded third packet to the second UEvia the sidelink channel.
 7. The method of claim 1, further comprising:receiving an indication of a quantity of subpackets into which to divideeach packet for encoding using the rateless encoding algorithm, anindication of the rateless encoding algorithm, an indication of arateless decoding algorithm, an indication of a pool of transmissionresources for sidelink communications by the first UE, or anycombination thereof.
 8. A method for wireless communications at a seconduser equipment (UE), comprising: receiving, from a base station,signaling that indicates a first amount of redundancy for encoding usinga rateless encoding algorithm; receiving, from a first UE via a sidelinkchannel, a packet encoded using the rateless encoding algorithm and inaccordance with the first amount of redundancy; decoding the packetusing a rateless decoding algorithm that corresponds to the ratelessencoding algorithm; and transmitting, to the first UE based at least inpart on decoding the packet using the rateless decoding algorithm, amessage comprising packet-level information that indicates a sufficiencyof the first amount of redundancy for encoding using the ratelessencoding algorithm.
 9. The method of claim 8, further comprising:estimating a loss probability for the packet, wherein the packet-levelinformation that indicates the sufficiency of the first amount ofredundancy for encoding using the rateless encoding algorithm indicatesthe estimated loss probability for the packet.
 10. The method of claim9, wherein estimating the loss probability for the packet comprises:determining a first quantity of subpackets received by the second UEduring a time period and a second quantity of subpackets transmitted bythe first UE during the time period, the loss probability based at leastin part on a ratio between the first quantity of subpackets received bythe second UE and the second quantity of subpackets transmitted by thefirst UE during the time period.
 11. The method of claim 8, furthercomprising: estimating a loss probability for the packet; anddetermining a second amount of redundancy based at least in part on theestimated loss probability for the packet, wherein the packet-levelinformation that indicates the sufficiency of the first amount ofredundancy for encoding using the rateless encoding algorithm indicatesthe second amount of redundancy.
 12. The method of claim 11, whereindetermining the second amount of redundancy based at least in part onthe estimated loss probability comprises: identifying the second amountof redundancy based at least in part on an index value for a lookuptable, wherein the index value for the lookup table corresponds to theestimated loss probability.
 13. The method of claim 8, whereintransmitting the message comprising the packet-level information thatindicates the sufficiency of the first amount of redundancy comprises:transmitting, in the message, a request to increase a redundancy amount;transmitting, in the message, a request to decrease a redundancy amount;transmitting, in the message, an indication of whether the packet wassuccessfully decoded; or any combination thereof.
 14. The method ofclaim 8, wherein decoding the packet using the rateless decodingalgorithm comprises: identifying a set of encoded subpackets receivedfor the packet, the set of encoded subpackets comprising a firstquantity of encoded subpackets greater than or equal to a secondquantity of original subpackets encoded using the rateless encodingalgorithm; decoding the set of encoded subpackets to obtain a set ofdecoded subpackets comprising a third quantity of decoded subpackets,the third quantity greater than or equal to the second quantity; andattempting to obtain the packet based at least in part on the set ofdecoded subpackets, wherein a probability of success for decoding thepacket using the rateless decoding algorithm is based at least in parton a difference between the first quantity of encoded subpackets and thesecond quantity of original subpackets.
 15. The method of claim 8,further comprising: transmitting, to the base station and based at leastin part on at least one of a condition of the sidelink channel or aquality of service target associated with the sidelink channel, arequest to transmit the packet-level information that indicates thesufficiency of the first amount of redundancy for encoding using therateless encoding algorithm; and receiving, from the base station, agrant in response to the request, wherein the message comprising thepacket-level information that indicates the sufficiency of the firstamount of redundancy for encoding using the rateless encoding algorithmis transmitted based at least in part on the grant from the basestation.
 16. The method of claim 8, further comprising: receiving, fromthe base station, a request to transmit the packet-level informationthat indicates the sufficiency of the first amount of redundancy forencoding using the rateless encoding algorithm, wherein transmitting themessage comprising the packet-level information that indicates thesufficiency of the first amount of redundancy for encoding using therateless encoding algorithm is transmitted based at least in part on therequest from the base station.
 17. The method of claim 8, furthercomprising: receiving, from the first UE via the sidelink channel, asecond packet encoded using the rateless encoding algorithm and inaccordance with a second amount of redundancy different than the firstamount of redundancy, the second amount of redundancy different than thefirst amount of redundancy and based at least in part on the sufficiencyof the first amount of redundancy for encoding using the ratelessencoding algorithm.
 18. The method of claim 8, further comprising:receiving an indication of a quantity of original subpackets for thepacket encoded using the rateless encoding algorithm, an indication ofthe rateless encoding algorithm, an indication of the rateless decodingalgorithm, an indication of a pool of transmission resources forsidelink communications by the second UE, or any combination thereof.19. An apparatus for wireless communications, comprising: a memory; atransceiver; and at least one processor of a first user equipment (UE),the at least one processor in communication with the memory and thetransceiver, and the at least one processor configured to cause theapparatus to: receive, from a base station via the transceiver,signaling that indicates a first amount of redundancy for encoding usinga rateless encoding algorithm; encode a first packet using the ratelessencoding algorithm and in accordance with the first amount of redundancyto obtain an encoded first packet; transmit, via the transceiver, theencoded first packet to a second UE via a sidelink channel; receive,from the second UE via the transceiver, a message comprisingpacket-level information that indicates a sufficiency of the firstamount of redundancy for encoding using the rateless encoding algorithm;encode a second packet using the rateless encoding algorithm and inaccordance with a second amount of redundancy to obtain an encodedsecond packet, the second amount of redundancy different than the firstamount of redundancy and based at least in part on the sufficiency ofthe first amount of redundancy for encoding using the rateless encodingalgorithm; and transmit, via the transceiver, the encoded second packetto the second UE via the sidelink channel.
 20. The apparatus of claim19, wherein, to receive the message comprising the packet-levelinformation that indicates the sufficiency of the first amount ofredundancy, the at least one processor is configured to cause theapparatus to: receive, in the message, an indication of the secondamount of redundancy; receive, in the message, a request to decrease aredundancy amount for encoding using the rateless encoding algorithm,wherein the second amount of redundancy is less than the first amount ofredundancy; receive, in the message, a request to increase a redundancyamount for encoding using the rateless encoding algorithm, wherein thesecond amount of redundancy is greater than the first amount ofredundancy; or receive, in the message, an indication of whether thefirst packet was successfully decoded, wherein the second amount ofredundancy is based at least in part on the indication; or anycombination thereof.
 21. The apparatus of claim 19, wherein: to receivethe message comprising the packet-level information that indicates thesufficiency of the first amount of redundancy, the at least oneprocessor is configured to cause the apparatus to receive, in themessage, an indication of an estimated loss probability for the firstpacket; and the processor is further configured to cause the apparatusto determine the second amount of redundancy based at least in part onthe estimated loss probability.
 22. The apparatus of claim 21, wherein,to determine the second amount of redundancy based at least in part onthe estimated loss probability, the at least one processor is configuredto cause the apparatus to: identify the second amount of redundancybased at least in part on an index value for a lookup table, wherein theindex value for the lookup table corresponds to the estimated lossprobability.
 23. The apparatus of claim 19, the at least one processorfurther configured to cause the apparatus to: receive, from the secondUE via the transceiver, a second message comprising packet-levelinformation that indicates a second sufficiency of the second amount ofredundancy for encoding using the rateless encoding algorithm; transmit,to the base station via the transceiver and based at least in part onthe packet-level information that indicates the second sufficiency ofthe second amount of redundancy for encoding using the rateless encodingalgorithm, a request to switch from using the rateless encodingalgorithm to using a different rateless encoding algorithm for sidelinkcommunications; receive, from the base station via the transceiver, anindication of a second rateless encoding algorithm that comprises thedifferent rateless encoding algorithm; encode a third packet using thesecond rateless encoding algorithm to obtain an encoded third packet;and transmit, to the second UE via the transceiver, the encoded thirdpacket via the sidelink channel.
 24. The apparatus of claim 19, the atleast one processor further configured to cause the apparatus to:receive, via the transceiver, an indication of a quantity of subpacketsinto which to divide each packet for encoding using the ratelessencoding algorithm, an indication of the rateless encoding algorithm, anindication of a rateless decoding algorithm, an indication of a pool oftransmission resources for sidelink communications by the first UE, orany combination thereof.
 25. An apparatus for wireless communications,comprising: a memory; a transceiver; and at least one processor of asecond user equipment (UE), the at least one processor in communicationwith the memory and the transceiver, and the at least one processorconfigured to cause the apparatus to: receive, from a base station viathe transceiver, signaling that indicates a first amount of redundancyfor encoding using a rateless encoding algorithm; receive, from a firstUE via the transceiver and a sidelink channel, a packet encoded usingthe rateless encoding algorithm and in accordance with the first amountof redundancy; decode the packet using a rateless decoding algorithmthat corresponds to the rateless encoding algorithm; and transmit, tothe first UE via the transceiver and based at least in part on decodingthe packet using the rateless decoding algorithm, a message comprisingpacket-level information that indicates a sufficiency of the firstamount of redundancy for encoding using the rateless encoding algorithm.26. The apparatus of claim 25, the at least one processor furtherconfigured to cause the apparatus to: estimate a loss probability forthe packet, wherein the packet-level information that indicates thesufficiency of the first amount of redundancy for encoding using therateless encoding algorithm indicates the estimated loss probability forthe packet.
 27. The apparatus of claim 25, wherein, to estimate the lossprobability for the packet, the at least one processor is configured tocause the apparatus to: determine a first quantity of subpacketsreceived by the second UE during a time period and a second quantity ofsubpackets transmitted by the first UE during the time period, the lossprobability based at least in part on a ratio between the first quantityof subpackets received by the second UE and the second quantity ofsubpackets transmitted by the first UE during the time period.
 28. Theapparatus of claim 25, the at least one processor further configured tocause the apparatus to: estimate a loss probability for the packet; anddetermine a second amount of redundancy based at least in part on theestimated loss probability for the packet, wherein the packet-levelinformation that indicates the sufficiency of the first amount ofredundancy for encoding using the rateless encoding algorithm indicatesthe second amount of redundancy.
 29. The apparatus of claim 28, wherein,to determine the second amount of redundancy based at least in part onthe estimated loss probability, the at least one processor is configuredto cause the apparatus to: identify the second amount of redundancybased at least in part on an index value for a lookup table, wherein theindex value for the lookup table corresponds to the estimated lossprobability.
 30. The apparatus of claim 25, wherein, to transmit themessage comprising the packet-level information that indicates thesufficiency of the first amount of redundancy, the at least oneprocessor is configured to cause the apparatus to: transmit, in themessage, a request to increase a redundancy amount; transmit, in themessage, a request to decrease a redundancy amount; transmit, in themessage, an indication of whether the packet was successfully decoded;or any combination thereof.